Essential Natural Science 1

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Contents PAGE

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About this book . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Learning to learn Getting closer to the stars! . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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The Universe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Planet Earth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Learning to learn All creatures great and small . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

3 4 5 6 7

Living things . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Invertebrates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Vertebrates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 The plant and fungi kingdoms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 The simplest living things . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 Learning to learn Rock stars and instruments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

8 The Earth’s atmosphere . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86 9 The hydrosphere . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 10 Minerals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 11 Rocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 Learning to learn It’s elementary! . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128

12 13 14

Matter and its properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 Everything is matter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 Atoms and elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 Vocabulary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160 Key language . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164

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Learning to learn

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ABOUT THIS BOOK • Look at these illustrations. Match them to the units on the opposite page. Then look at the book, and check your answers. Unit .........................

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YOU ALREADY KNOW A LOT! Work with a partner. Try to answer these questions. THE UNIVERSE How many planets in our galaxy can you name?

THE EARTH How long does it take the Earth to rotate on its axis? And how long does it take to orbit the Sun?

INVERTEBRATES Can you name six invertebrates?

PLANTS Plants are autotrophic: they make their own food. What is the name of the process by which plants do this? THE EARTH’S ATMOSPHERE Can you name three meteorological instruments? What does each one measure?

THE HYDROSPHERE Water is present on Earth in gaseous, liquid and solid form. Name four different places where you can find water in nature.

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MINERALS Quartz is a mineral. Can you name any other minerals? Can you say what each is used for?

MATTER AND ITS PROPERTIES Oil floats on water. Which has the greatest density, oil or water?

THE STATES OF MATTER Look at these three drawings. They represent a solid, a liquid and a gas. Can you match each drawing to its state?

1 UNIT

The Universe

What do you remember? • What are the points of light in this photo? • What is the difference between … – a star and a planet? – a moon and a comet?

STUDY A UNIT Look at page 8, the first page of Unit 1 • What is the title of the unit? • How many different sections are there on the page? What are they about?

Key language

In this unit, you will … • Learn about the characteristics of the Universe • Calculate astronomical sizes and distances • Analyse the components of the Universe • Compare sizes: the Sun and the planets • Create a constellation poster

Describing Planets are spherical bodies which orbit the Sun. Asteroids are rocky objects which are irregular in shape.

Comparing Dwarf planets are smaller than planets. The Earth is larger than Mercury

Giving instructions Study the constellations. Research more about them on the Internet.

• What do you think you will learn about in Unit 1? Now look at the rest of Unit 1

Content objectives

8

• How many sections are there in this unit?

• What can you find on page 17? How is this useful?

• What are most of the illustrations about?

Symbols

• Some words are in bold. Why is this?

• The text is recorded on the CD.

• How many activities are there in this unit?

• The information you need is available on the CD.

• What will you do in the Hands on section, page 15?

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Getting closer to the stars! Telescopes are used to see objects that are too far away to be seen with the naked eye. They also provide a closer view of distant things. Astronomers use large telescopes to study the planets, stars, and other objects in space. Without telescopes, we wouldn’t know much about celestial bodies!

Lenses or mirrors? Telescopes with lenses are called refracting telescopes. Lenses bend the light. The largest telescopes use mirrors instead of lenses Telescopes with mirrors are called reflecting telescopes. Mirrors reflect light.

Look through this end. The things you observe seem closer! eyepiece: lens to view the image focus adjustment: move this to make the image clearer

Some telescopes are small enough to be carried in one hand. Others can be huge, bowl-shaped radio telescopes, more than 300 metres in diameter. This is longer than three football pitches!

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Optical telescopes consist of a long tube, with one end narrower than the other. They can “perceive” light, just like eyes.

tube

OOPS! Wrong end! objective lens: the lens closest to the object being viewed

How does a telescope work? Objects reflect light. This light enters our eyes, and we see the object. Optical telescopes have an objective lens: a curved piece of glass at the wide end. This lens bends the light from the object so that it forms an image – a picture of the object – inside the telescope. The light from this image then goes through the eyepiece, at the narrow end of the telescope. The eyepiece bends the light back again, so the object looks big.

tripod: three-legged stand to support the telescope

The Gran Telescopio Canarias (GTC), also called GranTeCan, is a 10.4 m reflecting telescope, located on a volcanic peak (2,400 metres) on the island of La Palma, Spain. It took seven years to construct!

Activities 1. Galileo Galilei invented the telescope. Why was this such an important discovery? What did astronomers know about the stars before then? 2. Research. Have you heard of the Hubble telescope? When was it built? Where is it? What pictures does it take?

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UNIT

1

The Universe

What do you remember? • What are the points of light in this photo? • What is the difference between … – a star and a planet? – a moon and a comet?

Content objectives

Key language

In this unit, you will …

Describing

• Learn about the characteristics of the Universe

Planets are spherical bodies which orbit the Sun. Asteroids are rocky objects which are irregular in shape.

• Calculate astronomical sizes and distances

Comparing

• Analyse the components of the Universe

Dwarf planets are smaller than planets. The Earth is larger than Mercury.

• Compare sizes: the Sun and the planets • Create a constellation poster

8

Giving instructions Study the constellations. Research more about them on the Internet.

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1. What is the Universe like? Scientists developed two different theories to explain what the Universe was like.

Activities 1. Find ten words in the word search.

M P I

L A N E T S

G R

L A A S A

L U A T S R P T K N E

• Geocentric theory nd

2 century BC: Ptolomy proposed that the Earth was the centre of the Universe. That is, the Sun, Moon and planets orbited the Earth.

• Heliocentric theory In 1542, Nicolas Copernicus proposed that the Sun was at the centre of the Universe.

In 1610, Galileo Galilei invented the telescope, and proved the Heliocentric theory: the planets and stars revolve around the Sun.

L

T T A E

Y S E N A H C

L

W O H B R X E

L

A T M S U N Y

I

Y M O O N L

G T

K E S W C P A E 2. Imagine an alien friend from another galaxy wants to write to you. Write your galactic address.

What makes up the Universe? The Universe is all the matter, energy and space that exists. The Universe is made up of galaxies which contain stars. Stars can have planetary systems made up of planets and satellites. Galaxies are separated by vast spaces.

Galaxies are a vast collection of stars, dust and gases, held together by the gravitational attraction between the components. They appear in groups called galaxy clusters. Scientists think the vast spaces between the galaxies are empty. Our galaxy, the Milky Way, belongs to the Local Group galaxy cluster. Stars form when clouds of gases are pulled together by gravitational forces. They are so hot inside that they emit heat and light. A galaxy can have up to five hundred thousand million stars. An enormous cloud of gas and dust, a nebula, surrounds the stars. Planets are bodies which orbit some stars. They do not emit light; they receive light from the star. They make up planetary systems. Our planetary system is the Solar System. It is made up of eight planets and one star, the Sun, as well as moons, comets and asteroids. The Solar System is located on a spiral arm of the Milky Way. Natural satellites orbit some planets. The Earth’s natural satellite is the Moon.

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2. How big is the Universe? The Earth seems huge, but, in reality, it is small compared to the Sun. The Sun is only one of the millions of stars in the Milky Way. To imagine the size of the Universe, use these comparisons with everyday objects.

Activities 3. Express the distance of Mercury, Mars and Pluto from the Sun in kilometres.

• Imagine the Sun is the size of a pea. • The closest star is another pea, five hundred and forty kilometres away from the first pea. • The Earth is like a particle of dust situated two metres away from the first pea. • The Milky Way contains one hundred thousand million peas which form a circle with a radius of seven million kilometres. What units of measurement do astronomers use?

Mars

Mercury

Pluto

4. Research the term light-year. Why is it used in astronomy?

Did you know that...?

• Astronomical unit (AU). This is the distance from the Earth to the Sun. Approximately 150 million kilometres. Compare the distance of these planets from the Sun: – Mercury: 0.4 AU – Mars: 1.5 AU – Pluto: 39.4 AU • Light-year. This is the distance light travels in one year. Light travels 300,000 km in one second or 9.5 trillion km in one year.

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Source of light

Time to reach the Earth

the Sun

8 mins. 20 sec

Centauri, the nearest star

4 light-years

Betelgeuse

500 light-years

The radius of the Sun is 109 times greater than the radius of the Earth.

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3. What makes up the Solar System? The Solar System was formed approximately five thousand million years ago from the gas and dust of a nebula. Our Solar System is made up of the Sun, eight planets with their satellites, dwarf planets and small solar system bodies. The Sun is the central body. • The Sun consists mainly of two gases: hydrogen and helium. It is the closest star to Earth. • Planets are spherical bodies which revolve around the Sun. They all move in elliptical orbits, held by the gravitational force of the Sun. Planets are much larger than other celestial bodies which orbit the Sun. Mercury, Venus, Earth and Mars are made up mainly of rock. Jupiter, Saturn, Uranus and Neptune are made up mainly of gases.

The planets in the Solar System Planet

Distance from Sun (AU)

Period of rotation

Period of revolution

Mercury

0.39

58.65 days

88 days

Venus

0.72

243 days

224.6 days

Earth

1.00

23 h 56 mins

365.25 days

Mars

1.52

24 h 37 mins

1.88 years

Jupiter

5.20

9 h 55 mins

11.86 years

Saturn

9.54

10 h 40 mins

29.46 years

Uranus

19.19

17 h 14 mins

84.07 years

Neptune

30.06

16 h 7 mins

164.82 years

Activities 5. Which planet … • • • •

• Dwarf planets are spherical bodies which orbit the Sun. They are smaller than planets. • Small solar system bodies are other celestial bodies which orbit the Sun. They include asteroids, comets and satellites. Satellites orbit planets and consist of rock.

takes the longest to orbit the Sun? is the fastest to orbit the sun? has the longest days? has the shortest days?

6. Why is a “day” on Venus longer than its “year”? 7. What is an orbit? 8. What do you call the imaginary plane of the Earth’s orbit?

How do the planets move? Celestial bodies like the Earth, have two types of movement: Rotation. Celestial bodies spin or rotate on an invisible axis. This invisible line is called the rotational axis.

Revolution. Celestial bodies revolve around other celestial bodies.

Orbit. A curved path which a celestial body follows in its revolution around another celestial body. The orbit of the Earth around the Sun is an ellipse.

ecliptic plane

rotational axis of the Moon rotational axis

terre strial orbit

lunar orbit

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Mercury Diameter: 4,880 km

Venus Diameter: 12,104 km

Earth Diameter: 12,740 km

Mars Diameter: 6,794 km

4. Which are the inner planets? The inner planets are the four planets closest to the Sun: Mercury, Venus, the Earth and Mars.

The Earth is the only planet that has life on it. The other planets are too hot or too cold.

In 2004, the robots Spirit and Opportunity landed on Mars. They investigated the possible existence of water. INNER PLANETS

Did you know that...? Pluto, Ceres and Eris are dwarf planets. Pluto used to be considered a planet. In 2006, the International Union of Astronomers reclassified it as a dwarf planet.

Terrestrial or rocky planets: the crust and mantle are made of rock. The core is metallic Mercury

Venus

Earth

Mars

Diameter (Earth = 1)

0.382

0.949

1

0.532

Diameter (km)

4,880

12,104

12,740

6,794

⫺180 to 430 ºC

465 ºC

⫺89 to 58 ºC

⫺82 to 0 ºC

none

CO2

N2+O2

CO2

0

0

1

2

no

no

no

no

the smallest and closest to the Sun

rotates in opposite direction

the only planet with life

very thin atmosphere

Average surface temperature (ºC) Atmosphere Satellites Rings Interesting characteristics

Ceres

CO2 ⫽ carbon dioxide

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N2 ⫹ O2 = nitrogen⫹ oxygen

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Uranus Diameter: 51,118 km

Saturn Diameter: 120,536 km

Jupiter Diameter: 142,984 km

5. Which are the outer planets? Jupiter, Saturn, Uranus and Neptune are the four outer planets. They are called gas giants because they consist mainly of gases.

Neptune Diameter: 49,492 km

Saturn’s rings are made up of small particles, mostly ice.

OUTER PLANETS

Activities

Gas giants: they consist mainly of gases

9. Which planet … Jupiter

Saturn

Uranus

Neptune

11.209

9.44

4.007

3.883

142,984

120,536

51,118

49,492

⫺150 ºC

⫺170 ºC

⫺200 ºC

⫺210 ºC

H2⫹He

H2⫹He

H2⫹He

H2⫹He

63

59

27

13

yes

yes

yes

yes

largest planet, most satellites

system of rings

rotational axis is almost horizontal

greatest distance from the Sun

• has the most satellites? • is closest to the Sun? • supports life?

H2 ⫽ hydrogen

• is the largest in the Solar System? • spins on its axis in the opposite direction? 10. If you live on Venus, will the Sun rise in the East and set in the West?

He ⫽ helium

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Pluto Mercury

Mars

Earth comet

Neptune

Saturn Jupiter

Venus Uranus Asteroid belt

The Solar System. Observe the elliptic paths of the planets’ orbits around the Sun. Notice that the orbit of Pluto, a dwarf planet, is more inclined.

6. What are small Solar System bodies? There are two main types: asteroids and comets. They orbit the Sun. • Asteroids are rocky objects which are irregular in shape. They can be several hundred kilometres in diameter, but most are only a few metres wide. Asteroids orbit around the Sun. Most of them are between the orbits of Mars and Jupiter. This area is called the asteroid belt. • Comets are small bodies that travel around the Sun in highly elliptical orbits. They are irregular in shape. The nucleus is made up of a mass of ice, dust and gas. When comets travel close to the Sun, some of the ice evaporates, creating the long, bright tails of the comets.

Activities 11. Compare the main characteristics of the inner and outer planets. 12. Describe an inner or outer planet. Your partner will identify it.

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This inner planet This outer planet

is smaller / larger than is the largest / smallest. has (no)

the Earth. … satellites.

The atmosphere

is made up of

carbon dioxide. helium. …

Halley’s comet has a bright tail. It was named after the English scientist Edmund Halley. He was the first scientist to calculate the orbit of this comet. Halley’s comet will next be visible from Earth in 2061.

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Hands on Prepare a constellation poster Constellations are imaginary patterns of bright stars. All societies have invented constellations. The Ancient Greeks invented the constellations we call the twelve signs of the zodiac. There are 88 official constellations. However, most of them do not really look like the mythical figures they represent. The night sky looks different in the Northern and Southern Hemispheres. The position of the constellations changes with the seasons because of the movement of the Earth.

Cassiopeia

Orion

Ursa major

Gemini

1. Study these constellations. Which ones can you see in the night sky where you live?

The constellation Orion

2. Choose one of the constellations and make a poster. a. Find more information in encyclopedias or on the Internet. b. Draw the constellation, or cut out a drawing or a photo of it. c. Write some sentences about the constellation.

Orion represents the hunter. The three stars in the middle are his belt. His sword hangs from his belt. You can see his sword and his bow.

Activities 13. Look up the constellation for your sign of the zodiac.

14. Choose another constellation. Research more about it on the Internet.

a. Find out where and when it is most clearly visible in the sky. Is it in the Northern or the Southern Hemisphere? b. Write the dates associated with this sign.

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Activities 21. Talk about astronomical distances with a partner.

15. Label each diagram with the name of …

How far away is … from …? It is … km / … light-years away.

a. a theory of the universe b. the person who proposed the theory. b

a

Astronomic distances from the Earth Object

16. Make a drawing of the Solar System and label it: the Sun, the inner planets, the outer planets, Pluto and the asteroid belt. 17. Make a timetable of your daily activities on these planets. Give an approximate duration for each. • Earth. Rotation: 24 hours • Mercury. Rotation: 58.65 Earth days • Jupiter. Rotation: 9.841 Earth hours

Distance

space station

300 km

weather satellite

36,000 km

the Moon

384,000 km

the Sun

150,000,000 km

Pluto

6,000,000,000 km

Alpha Centauri

4 light-years

22. Research the latest astronomic discoveries. Report your findings to the class. 23. This drawing shows the positions of a comet in orbit. When a comet gets close to the Sun, why does it develop a tail? Why does an asteroid not?

Duration on … Activities

Earth

Mercury

Jupiter

18. What two types of movement do all planets have? Describe them. 19. Describe the composition, temperature and movement of the Sun. 20. Make an illustrated list of the planets. Write them in order: start with the closest one to the Sun. a

b

c

24. Draw a diagram of the Solar System seen from above. Include the rotation and revolution movements of each planet. 25. Copy and complete to situate the Moon in the Universe: The Moon is a satellite of … which belongs to the planetary system called … . The star of this planetary systems is … . It belongs to a galaxy called … . This galaxy is part of the galaxy cluster called … .

d e f

16

g

h

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THE UNIVERSE

What should you know?

1

Early concepts

• Geocentric theory: the Earth is the centre of the Universe. The Sun, Moon, stars and planets revolve around the Earth. • Heliocentric theory: the Sun is the centre of the Universe. The Earth, planets and stars revolve around the Sun.

Components

• Galaxies are grouped together in galaxy clusters. • Galaxies contain thousands of millions of stars. • Stars are massive spherical bodies of gases. Some stars have planetary systems with planets, satellites, asteroids and comets.

Units of measurement

• Astronomical unit (AU): the distance between the Earth and the Sun, about 150 million kilometres. • Light-year. The distance that light travels in one year: about 9.5 trillion kilometres.

The Solar System

The Solar System is the planetary system of our Sun. It consists of: • The Sun: a medium-sized star in the Milky Way galaxy. • Planets: Inner: Mercury, Venus, Earth and Mars. All are rocky. Outer: Jupiter, Saturn, Uranus, and Neptune. All are gaseous. • Dwarf planets: Pluto, Ceres, Eris • Natural satellites: celestial bodies which revolve around planets and dwarf planets. • Small Solar System bodies Asteroids: small rocky bodies which orbit the Sun. Some form belts. The asteroid belt: a band of asteroids between the orbits of Mars and Jupiter. Comets: masses of ice and rock found beyond the orbit of Pluto.

Projects INVESTIGATE: Could Mars support life?

First, list the factors that make life possible on Earth. Then, investigate this website: http//solarsystem.nasa.gov/planets/profile.cfm?Object=Mars WEB TASK: Do you want to visit Mercury, Jupiter or Mars?

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UNIT

2

Planet Earth

What do you remember? • In this photo, what does each colour correspond to? • Is the Earth an outer or an inner planet? • What is the interior of the Earth like? • Where does life exist on Earth: in the geosphere or the biosphere?

Content objectives

Key language

In this unit you will …

Describing

• Learn about the Earth’s characteristics

Water exists in three states. It takes 28 days to orbit the Earth.

• Identify lunar phases • Describe the geosphere • Learn about the Earth’s “spheres” • Reproduce conditions of solar and lunar eclipses

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Expressing cause and result This causes the sequence of day and night. This makes the seasons occur.

Comparing The days get shorter. Ocean trenches are the deepest areas.

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1. What is the Earth like? The Earth is special for many reasons. The Earth is the only planet with: • an atmosphere containing oxygen

1. Draw a diagram of the Earth, as seen from space. Draw two people: one at the North Pole and one at the South Pole.

• an average temperature of 15ºC • a water cycle • life as we know it All these characteristics make the Earth a unique planet in the Solar System. • The atmosphere consists of a mixture of gases. Nitrogen and oxygen are the most abundant. Oxygen is essential for plant and animal respiration. There is also carbon dioxide, essential for photosynthesis. • The average temperature is 15°C on the Earth’s surface. This is possible because of the distance from the Sun and the composition of the atmosphere. • Water exists in three states (ice, liquid, water vapour) due to temperature variations. These variations make the water cycle possible.

Photo of the Earth and the Moon taken by satellite.

Activities

2. Find out the mixture of gases and the average temperatures of Venus and Mars. Why do you think life is only possible on Earth?

• The Earth has a relatively large natural satellite, the Moon. The gravitational attraction of the Moon causes ocean tides. • The Earth’s magnetic field protects living beings from dangerous solar radiations. • Conditions exist for life. Thousands of millions of years of evolution have produced the variety of species there are today. This includes humans. • There is considerable geological activity on the Earth: earthquakes, volcanoes, mountain building, erosion, etc.

Volcanoes are proof of intense geological activity.

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2. How does the Earth move? direction of rotation

The Earth moves in two different ways: Equator

• Rotation: The Earth rotates on a slightly tilted axis, always in the same direction. This rotation causes the sequence of day and night.

North Pole plane of the Earth’s orbit

Sun’s rays

• Revolution: The Earth’s revolution around the Sun is an ellipse. It takes 365 1⁄4 days to complete the revolution. This is one year.

Northern Hemisphere

Summer Solar rays strike perpendicular to the Earth’s surface and produce more heat.

D

ay

rotational axis 23.5°

ht Nig South Pole Southern Hemisphere

The rotation of the Earth. It is day on the half of the Earth facing the Sun. It is night on the half facing away from the Sun.

What causes the seasons on Earth? Winter

Two factors combine to cause the seasons: • the revolution of the Earth around the Sun • the Earth’s axis is tilted at an angle of about 23.5º

Solar rays strike the Earth at a steeper angle and produce less heat.

The tilt of the axis causes differences in temperature and in the duration of day and night. The Sun’s rays strike the Earth in different ways depending on the seasons. The tilt of the axis makes the seasons occur at different times of the year in the Northern and Southern Hemispheres. Spring. The days get longer and the nights get shorter until 21st June the longest day.

Spring equinox 21st March

Winter. The days get longer and the nights get shorter. On 21st March, day and night are the same length.

Winter solstice 21st December

Summer solstice 21st June

Summer. The days get shorter and the nights get longer. On 22nd September day and night are the same length.

Autumn equinox 22nd September

Autumn. The days get shorter and the nights get longer until 22nd December- the shortest day.

The seasons in the Northern Hemisphere

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3. How does the Moon move? The Moon moves in two different ways:

1

• Rotation. The Moon takes 29.5 days to rotate once on its axis: a “lunar day”.

8

• Revolution. The Moon takes about twenty-eight days (twenty-seven days and eight hours) to orbit the Earth once.

2

7

3

A “lunar month” is the period of time between two new moons. It is about 29.5 days. A “lunar day” is as long as a “lunar month”. As a result, the same side of the Moon always faces the Earth.

6 4 5 The same side of the Moon always faces the Earth. The red dot indicates the dark or hidden side. It is never visible from Earth.

Activities 3. Draw a diagram to show the phase of the Moon in the Northern Hemisphere today. 4. When is there a New Moon? 5. Draw a diagram of the phases of the Moon in the Southern Hemisphere.

The phases of the Moon New Moon

Last Quarter

The Moon is between the Sun and the Earth, so the Moon is not visible. The dark side (not illuminated) faces the Earth. The Moon rises and sets with the Sun, but you cannot see it from Earth.

Half the side is lit by the Sun. The illuminated part slowly shrinks. It rises at midnight and sets at noon.

First Quarter

Full Moon

Half the side is lit by the Sun. The illuminated part slowly increases. It rises at noon and sets at midnight.

When the Earth is between the Moon and the Sun, the entire Moon is visible. The illuminated side faces the Earth. It rises and sets with the Sun.

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Hands on Reproducing eclipses If the Moon passes between the Sun and the Earth, and blocks off the sunlight, a solar eclipse occurs. If the Moon passes behind the Earth, so the Earth prevents sunlight from reaching the Moon, a lunar eclipse occurs.

Materials

the Sun

the Moon the Earth

1. Reproduce a solar eclipse. Position the planets: the Moon should block the Sun’s light and project a shadow on the Earth.

2. Reproduce a lunar eclipse. Position the planets: the Earth should block the Sun’s light and project a shadow on the Moon. Remember: a lunar eclipse can only take place during a full moon.

3. In your notebooks, copy the diagrams for both eclipses. umbra

penumbra

penumbra

Earth

Moon

Sun

Sun

Moon

Earth

Solar eclipse

Activities 6. Find out when the next solar and lunar eclipses will take place. Visit this site: http://sunearth.gsfc.nasa.gov/eclipse/eclipse.html 7. How must you protect your eyes when observing a solar eclipse?

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umbra

Lunar eclipse

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4. How many “spheres” make up the Earth? The Earth is the only known planet which contains water and living things. It is made up of four interrelated parts or “spheres”. These are: • The geosphere. The solid part which includes the crust, mantle and core. The upper 100 km of the geosphere is called the lithosphere: it is the most rigid part. • The atmosphere. The air: a layer of gases which envelops the Earth.

• The hydrosphere. All the water on the Earth. • The biosphere. All the living things which inhabit the Earth.

The geosphere The geosphere consists of three concentric layers: the crust, mantle and core. The crust and the upper mantle make up the lithosphere. The crust is the outer layer of rock. The most abundant minerals are silicates. • The continental crust makes up the continents. Granite is the most common rock. • The oceanic crust makes up the ocean floor. It was created by intense volcanic activity at mid-oceanic ridges. Basalt, a volcanic rock, is the most common rock.

mantle outer core (liquid) inner core (solid)

The mantle is the middle layer, below the crust. It lies 2,900 km below the surface. It is made up of mostly solid rock material. The temperature is higher here, from 1,000ºC to 4,000ºC, so some areas are melted rock. The core is the centre of the Earth, below the mantle. It is made up mainly of iron. The temperature is over 4,000°C. The outer core is liquid. The inner core is solid.

Activity

continental crust (thickness varies from 7 to 70 km)

oceanic crust (thickness varies from 7 to 10 km)

8. Show the three layers of the geosphere in a diagram. Label each layer: main components, temperature and state: solid or liquid. Label the two types of crust.

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5. What is the surface of the Earth like? From outer space, the Earth looks blue because of the vast expanses of water on its surface. The distribution of materials that make up the Earth’s crust form the different types of land relief.

Ocean floor relief features • The average depth is 4,500 m. • The main relief features are: – Oceanic (mid-oceanic) ridges. Chains of submarine mountains with intense volcanic activity. Example: the Mid-Atlantic ridge. – Oceanic trenches. The deepest areas of the ocean. Example: Mariana Trench: 11,034 m deep. – Abyssal plains. The largest plains on the planet: 4,000 or 4,500 m deep. – Submarine volcanoes may create volcanic archipelagos. Examples: the Canary Islands, the islands of Hawaii.

Continental relief features • The average altitude is 600 m. • The three main relief features are: – Mountain ranges. Chains of high mountains. Examples: the Himalayas in Asia or the Andes in South America. – Great plains. Large extensions of flat land. Examples: the Amazon plain in South America or the Sahara desert in Africa. – Continental shelves. The areas near the coastline, under the sea, that are made of continental crust, not oceanic crust. These areas slope down from the coastline to a few kilometres out to sea, to a depth of about 200 metres.

Oceanic relief forms can rise up to 2 km from the ocean floor. In some places they appear above the water to form islands. Example: Iceland.

Cross-section of the Earth’s surface

mountain range

continental great plain

submarine volcano mid-oceanic ridge

continental shelf

abyss

abyssal plain

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oceanic trench

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6. What are the other three Earth “spheres”? Apart from the geosphere, the other three Earth “spheres” or systems are the atmosphere, the hydrosphere and the biosphere. The atmosphere The atmosphere is the layer of air which surrounds the Earth. Air is a mixture of gases. The main components are: nitrogen (78 %) and oxygen (21 %). Oxygen is one of the necessary conditions for life. There are also small quantities of carbon dioxide (CO2) and other gases.

Activities 9. Say a relief feature. Your partner says if it is continental or ocean floor. 10. Which continental feature is under the sea? 11. Describe the four different spheres that make up the Earth. List examples of features in each sphere.

The hydrosphere The hydrosphere is all the water on, under and above the Earth. The hydrosphere is made up almost exclusively of liquid water, but also snow and ice. Other materials in the hydrosphere are the mineral salts in water. Sea water is very rich in mineral salts, but fresh water has few salts. The biosphere The biosphere includes all the living things which inhabit the Earth. Living things influence the physical and chemical changes in the Earth. For example: • In the Earth’s crust: Animals live in the ground and plants take mineral salts from the soil. Plant roots can break up rocks. • In the atmosphere: Microorganisms which live in the soil produce nitrogen. Oxygen is produced during photosynthesis by plants, algae and some bacteria. Many living things cause evaporation. • In the hydrosphere: Living things contain water. Plants take water from the ground. Many organisms live in aquatic environments.

Did you know that...? The water cycle refers to how water evaporates, rises, condenses, falls to the Earth as rain or snow and moves around. This cycle was described 2,500 years ago byThales.

Coral produces exoskeletons which accumulate to form a rocky shelf. This atolon in Tahiti is made up of living things.

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Activities 12. Draw the Earth. Include an arrow pointing in the direction in which it revolves. When does the Sun rise where you live?

18. The Moon has a dark side because each time it completes a turn around the Earth, it rotates on its own axis. This takes 28 days.

13. Draw the Earth and its orbit. Show four positions.

With a partner, demonstrate the movement of the Moon around the Earth.

a. Indicate the solstices and the equinoxes. Divide the orbit into four parts: one for each season in the Northern Hemisphere. b. Colour each season a different colour. Tip: summer begins with the summer solstice and ends with the spring equinox. 14. Why is the Sun higher over the horizon at noon in summer than in winter? Does this occur at the same time of year in both hemispheres? 15. Think about the seasons. Use this information: Solstices. summer / winter Equinox. spring / autumn. The Sun is above the Equator. Day and night are the same length. a. When it is summer in the Southern Hemisphere, what season is it in the Northern Hemisphere? And when is it spring there? b. What causes this difference in the seasons?

19. What are the main differences between the continental crust and the oceanic crust? 20. Match each phrase to: geosphere, hydrosphere, atmosphere or biosphere. • water in a river • waves in the sea • sand on a beach • fish, birds, plants or other living things • the air you breathe • clouds 21. Two friends are collecting rocks. Who is right? Why? Girl: These rocks belong to the geosphere. Boy: No, they belong to the lithosphere. 22. Think about the Earth’s rotation and answer. a. Why are days longer in the summer?

16. Match each picture of the Moon with a number in the diagram below. A

B

C

D

E

F

G

H

1

8 7

2

6

3 5

4

17. The ecliptic is an imaginary plane. It passes through the centre of the Earth and the centre of the Sun. a. Does it go through the centre of the Moon? b. Does it pass through only sometimes? How often? When?

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b. Why do days and nights last for six months at the poles? c. How are day and night produced? Make a drawing to show this. 23. Identify: summer solstice, winter solstice. Explain your answer.

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2

• • • •

It has an intense magnetic field. The atmosphere contains mainly nitrogen, oxygen and carbon dioxide. The average temperature is 15ºC. Water exists on Earth in solid, liquid and gaseous states. There is a water cycle. • The Earth has one large natural satellite, the Moon. • Life exists on Earth.

The Moon, the Earth’s satellite

• Rotation. The Earth rotates on its axis. The axis is tilted 23.5º. This rotation creates day and night. • Revolution. The Earth revolves around the Sun. Its orbit is elliptical. These two movements and the Earth’s tilt cause the seasons. Other consequences are the differences in the length of day and night.

The Moon takes almost 28 days to orbit the Earth. It takes the same length of time to rotate once on its axis. Lunar phases: New Moon, First Quarter, Full Moon and Last Quarter. • Solar eclipse: the Moon blocks the light from the Sun. • Lunar eclipse: the Earth blocks the light from the Sun so it does not reach the Moon. The gravitational attraction or “pull” of the Moon on the oceans causes the tides.

The four Earth “spheres”

THE EARTH

Movements

Special characteristics of Earth

What should you know?

Geosphere: the solid part of the Earth. It consist of the: • Lithosphere: the crust and the upper mantle. – Continental crust: makes up the continents. – Oceanic crust: makes up the ocean floor. The Earth’s surface is made up of continental features and ocean floor features. • Mantle: the middle layer of the Earth, made of rock. • Core: the centre of the Earth, made up of metals. Outer core: liquid. Inner core: solid. Atmosphere: the layer of air which surrounds the Earth. It consists of a mixture of gases. Hydrosphere: all the waters on the Earth. Biosphere: the part of the Earth where living things exist. Living things can be aquatic or terrestrial.

Projects EXPERIMENT: Think about the geosphere.

• Shake together a mixture of gravel, cork and water. Allow this to settle. Observe the separation in layers by density. • Compare with the diagram of the geosphere on page 23. Identify the crust, mantle and core represented in your experiment. WEB TASK: Find out about artificial satellites.

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All creatures great and small The Earth is the only planet we know which is capable of supporting life. 1. How many living creatures can you find?

2. Check your answer in the word snake.

fr

e og

le p

ha n t f lo

we

ra

nt

bu

tte

r f lymon

y ke

tre

3. Now put them into three different groups. Explain why you chose them.

28

o em

s s f e r n f ungi

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eyepiece

tube

Look at these drops of water from the pond. Can you see anything in them? Some living things are so small they cannot be seen with the naked eye. They can only be seen through a microscope.

nosepiece arm

objective lenses

coarse focusing knob

cover slip

stage

4. Match each task, a-f, to its corresponding part of the microscope.

iris diaphram

fine focusing knob

a. This magnifies the specimen b. This increases the amount of light

base

light source

c. This is where you put the specimen

Optical microscope

d. This is where you look through e. This is where you change the magnification f. This is used for fine focusing

5. Look at the pond water through the microscope. What a surprise! Use the code to write the vowels and discover the names of the microorganisms. Code: A__ E__ I__ O__ U__

__ __GL__N__

PR__T__Z__ __

B__CT__R__ __

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UNIT

3

Living things

What do you remember? • Can you name any of these living things? • Classify them into groups: plants, animals, vertebrates, invertebrates. • What do all living things do? • What is the animal kingdom? • What kingdom do human beings belong to?

Content objectives

Key language

In this unit, you will …

Expressing facts

• Define the characteristics of living things • Describe cell structure and cell functions • Classify unicellular and multicellular living things • Classify living things into five kingdoms • Make slides to study cells

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Living things feed, reproduce and interact.

Making impersonal statements Cells are organised into levels.

Expressing purpose Photosynthesis enables plants to obtain energy. Water is used to transport substances.

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1. What is biodiversity? Biodiversity is the variety of life on Earth in all its forms. Biodiversity is the result of a slow process called evolution. Evolution began with the first life forms and still continues today. Species change, and adapt to the environment. Scientists believe there may be more than thirty million species. Approximately two million species have been classified.

What factors can reduce biodiversity?

Biodiversity varies tremendously throughout the world. It is influenced by climate zones and habitats. For example, more than half the world’s species live in tropical rain forests and coral reefs. Some countries have many different climate zones and habitats. As a result, they have more biological diversity. For example, Spain has more biological diversity than other European countries. 3

Whole species of living things become extinct every day for these four factors: 1

Destruction of habitats caused by deforestation, the construction of roads, dams, etc.

2

Did you know that...? Rain forests have the greatest biodiversity.

Uncontrolled hunting and fishing endangers many species: for example the Iberian lynx (Lynx pardinus) is in danger of extinction.

Pollution of water, soil and the atmosphere, caused by agricultural, industrial and urban development.

4

Introduction of exotic species can destroy local species. For example, the river crab.

Activities 1. True or false? Biodiversity refers to all living things. 2. Why does biodiversity vary throughout the world? 3. Match each photo with a factor that reduces biodiversity. a. pollution b. destruction of habitats c. uncontrolled hunting d. introduction of exotic species

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2. What do all living things have in common? All living things have a similar chemical composition. All living things also carry out three functions: nutrition, interaction with the environment and reproduction. Nutrition refers to all the processes which enable living things to obtain the energy and matter they need to live. Living things can be classified into two groups depending on how they feed. • Autotrophs produce the organic substances which they need from inorganic substances. They take substances like water, mineral salts and carbon dioxide from the soil and the atmosphere. To obtain these substances, autotrophs need energy. They get energy from sunlight through a process called photosynthesis. Chlorophyl enables them to do this. Plants, algae and some bacteria are autotrophs. • Heterotrophs feed on organic matter which is already elaborated: for example, living things or their remains. Animals, fungi, some bacteria and all protozoa are heterotrophs. Interaction with the environment: all the processes which enable living things to react to changes in their environment. For example: plants grow towards the light; animals flee from predators. Reproduction: refers to all the processes which enable living things to create new living things. There are two basic types: • Asexual reproduction involves one living thing. For example: a sponge can produce buds which give rise to new sponges. • Sexual reproduction involves living things of different sexes. Each one provides a sex cell or gamete. The two sex cells join to form the first cell of a new living thing, the zygote.

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What function is this cheetah carrying out?

Why are all the flowers following the Sun? What function are they carrying out?

Activities 4. Complete: Heterotrophs feed on ... . Autotrophs obtain ... . Sexual reproduction involves ... . Asexual reproduction involves ... . 5. Test your partner. Ask questions: Which processes enable living things to ... ... create new living things? ... adapt to their environment? ... obtain the energy they need?

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3. What are living things made up of? All living things are made up of chemical substances. Carbon (C), oxygen (O), hydrogen (H), and nitrogen (N) make up about 95 % of all living matter. Combinations of these elements form molecules of living matter called biomolecules. Living things are made up of two kinds of substances: inorganic and organic.

Inorganic substances Inorganic substances do not contain carbon. They are present in living things and non-living things. The principle inorganic substances are: • Mineral salts have various functions: they make up different structures, like shells, bones and teeth. They are present in internal fluids, like tears, sweat and blood.

• Water is the most abundant substance in living things. Living things obtain water directly by drinking it, or indirectly from substances that contain water. Plants obtain water from the environment. Water is necessary for chemical reactions and to transport all other substances.

Organic substances Organic substances are unique to living things. Carbon is their principal element. Organic substances present in living things are: Biomolecules Glucides

Example

Use/Function

glucose cellulose

Lipids

fatty acids cholesterol

Proteins

haemoglobin antibodies keratin

Nucleic acid

DNA RNA

Activities

to provide energy to make structures to provide energy to make structures to transport oxygen to fight microorganisms that cause disease to make structures: hair, nails to control cell function and heredity

Organic and inorganic substances are present in different amounts in plants and animals. Plants

Animals water 60 %

water 74 %

lipids 0.8 %

mineral salts 3.2 %

proteins 3.2 %

glucides 19 %

lipids 20 %

glucides 0.6 % mineral salts 3.4 %

proteins 16 %

6. Compare organic and inorganic substances:

… substances are …; … substances have … 7. Ask questions about organic and inorganic substances. For example:

How are (lipids) used by living things? They are used to … 8. Use the pie charts to calculate, in grams, the approximate value of each group of biomolecules: a. Weigh yourself, then calculate the biomolecules in your body. For example, 100 kgs = 60 kg water b. a sunflower: 2.250 grams.

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4. What are cells? Cells are the smallest unit of life. They are the structural and functional units for all living things. • All living things are made up of one or more cells. • Cells carry out the functions of nutrition, interaction with their environment and reproduction. • Most cells are very small. For example, skin cells are approximately one hundredth of a millimetre in size. • All cells come from other cells.

Did you know that...? Robert Hooke was the first person to use the term cells. In 1665, with this microscope, he observed cavities in a thin slice of cork, and called them cells.

What are the two basic types of cells?

nucleus cytoplasm cytoplasm organelles organelles

genetic material

cell membrane

cell membrane

Eukaryotic cell

Prokaryotic cell

• Prokaryotic cells have no nucleus. They have no nuclear membrane. Genetic material is dispersed throughout the cytoplasm. They are simpler and smaller than eukaryotic cells. Bacteria are made up of prokaryotic cells.

• Eukaryotic cells have a nucleus, separated from the cytoplasm by the nuclear membrane. Algae, protozoa, fungi, animals and plants have eukaryotic cells.

How is a cell organised? • The cell membrane covers the whole cell. • Cytoplasm is the inside of the cell. It is a jelly-like substance. Many of the chemical reactions of the cell take place here. Organelles are small structures in the cytoplasm. They are responsible for respiration, making and storing nutrients, etc. • Genetic material controls and regulates how cells work. This DNA contains the hereditary information that is passed from one cell to the daughter cell. DNA makes up the chromosomes.

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Activity 9. Read the chart, then make sentences to describe the cells: Eukaryotic cells are found in animals. Eukaryotic cells

Prokaryotic cells

found in

animals

bacteria

size

big

small

nucleus

yes

no

complexity

complex

simple

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5. How do animal and plant cells differ? Both animals and plants have eukaryotic cells, but there are some differences. • Plant cells have a rigid cell wall which surrounds the plasmatic membrane. The cell wall gives the cell its shape and strengthens it. • Plant cells are usually polyhedral, but animal cells are various shapes: round, square, star-like.

• Plant cells have unique organelles called chloroplasts which are responsible for photosynthesis. • The nucleus of plant cells is usually found on one side. A vacuole takes up most of the space. Animal cells also have vacuoles, but they are smaller. Plant cell

Animal cell Cell membrane. Like a skin around the cell. It keeps the cell together and controls what passes in and out. Nucleus. Contains genetic material. Cytoplasm. Contains the organelles: mitochondria, vacuoles… Vacuoles. Like bags, surrounded by membranes where substances, mainly water, accumulate. Mitochondria. Where energy is obtained from nutrients.

Cell wall. A thick, rigid wall made of cellulose.

Chloroplasts. These store a green pigment, chlorophyll, which absorbs the Sun’s energy to elaborate organic matter during photosynthesis.

Activities 10. Make a Venn diagram: show the similarities and differences between animal and plant cells. 11. Draw and label an animal cell with all its parts.

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Hands on Making a hypothesis. Using a microscope to study cells A hypothesis is a proposal. It is used as a basis for reasoning. Scientists use experiments and observation to test the validity of a hypothesis. Hypotheses show the relationship between two or more facts. For example: we know that cell walls in plant cells are made of cellulose.

Cellulose is a rigid substance that holds the cell parts together in a polyhedral shape. Resulting hypothesis: If you observe cells through a microscope that are polyhedral in shape and joined together by thick walls, you know they are plant cells.

Making a specimen of plant cells

1

1. Take a moss plant specimen and use tweezers to remove a phyllode.

2. Place the phyllode on a slide. Add a drop of water. 3. Place the cover slip on the specimen, look through the microscope and draw the specimen. Use different magnifications. At higher magnifications you may be able to see and count the chloroplasts.

2

3

phyllodes

Making a specimen of animal cells

1. To obtain cells, rub the inside of your cheek gently with

1

2

a clean cotton bud.

2. Spread the cells on a slide and add a drop of water. 3. Stain the cells with methyl green or a similar dye. 4. Put the cover slip on, look through the

3

microscope and draw the specimen.

4

Check your hypothesis Notice that the plant cells have a polyhedral shape. The animal cells are irregular, and they are not joined together.

Activities 12. Label each plant cell indicating its magnification. 13. Imagine that your hypothesis were incorrect. What result would make this obvious? 14. Imagine you have an unidentified sample. Hypothesis: If this is a living thing, it will be made up of cells. Is this hypothesis correct? Can you use it to differentiate between living and non-living things? What would you do to classify the sample as living or non-living?

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6. How do living things differ? Living things can be classified into two different groups: unicellular and multicellular. • Unicellular living things have only one cell. They sometimes form colonies. Unicellular living things feed, interact with the environment and reproduce. Example: paramecia. • Multicellular living things have many different cells. Example: plants and animals.

Multicellular organisation

Activities 15. Describe one of the specialised cells. Your partner identifies it. For example: A: It has no nucleus. B: A red blood cell. 16. What is the difference between tissues, organs and systems? Example: ... are made up of...

muscle cell

Cells

Cells in multicellular living things are organised in levels. The cells work together to carry out the vital functions. • Cells are specialised: they have specific functions. Each type has a unique shape and structure. • Tissues are groups of cells with the same function. Example: muscle cells form muscle tissue. • Organs are groups of various tissues which act together. Example: a muscle is an organ made up of muscle tissue, nerve tissue, connective tissue and blood tissue. • Systems are made up of several organs. Example: the digestive system includes the stomach, the intestines, etc.

Tissue

muscle tissue

Organ

muscle

Muscular system

muscular system

Form and function of cells Specialised Cells

Sperm cells

Red blood cells

Neuron or Nerve cells

Root hair cells

have a tail (flagellum) so they can swim toward the ovum

consist mainly of haemoglobin to transport oxygen

are like wires with a lot of extensions so they can conduct and capture messages

are long and thin so they can absorb water and mineral salts from the soil

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7. What are the five kingdoms? Scientists use criteria for classification to organise living things into groups. Classification enables them to compare different living things. Scientist classify all living things into five kingdoms by three main criteria: type of cells, how the cells are grouped, and nutrition. Monera Kingdom

Protoctist Kingdom

Contains unicellular, prokaryotic organisms. They may be autotrophic or heterotrophic. Bacteria and cyanobacteria.

Contains unicellular and multicellular living things. They are all eukaryotes. They have no tissues. They may be autotrophic or heterotrophic. Protozoa, algae.

Plant Kingdom

17. Copy and complete the table to describe the five kingdoms.

Kingdom Moneran

Type of cells

Contains multicellular eukaryotes. They have tissues. They are heterotrophic. Animals: may be invertebrate or vertebrate.

Tissues

No tissues Eukaryotic

Heterotrophic

Plant Animal

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Autotrophic / Heterotrophic

Prokaryotic

Protoctist Fungi

Contains unicellular and multicellular living things. They are eukaryotes. They have no tissues. They are heterotrophic. Yeasts, moulds, mushrooms.

Animal Kingdom

Contains multicellular eukaryotes. They have tissues. They are autotrophic. Mosses, ferns, flowering plants.

Activity

Fungi Kingdom

They have tissues

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8. How are living things classified? Living things can be differentiated by the way they feed, reproduce, interact with their enviroment, etc. They are classified into different groups. The main group is the kingdom. Each kingdom is then divided into subgroups.

CLASSIFICATION

YOU

BECAUSE YOU...

Kingdom

Animal

Are a heterotroph, cells form tissues

Phylum

Chordate

Have a spinal chord

Sub phylum

Veterbrate

Are a chordate with a backbone

Class

Mammal

Have warm blood; babies drink mother’s milk

Order

Primate

Your thumbs and fingers work together

Family

Hominid

Walk upright

Genus

Homo

Talk, have a long childhood

Species

Homo sapiens

Are intelligent, have little body hair ...

This is how you are classified.

9. What is a species? A species is the first level of classification for living things. A species is a set of living things which are physically similar. They reproduce and usually have fertile descendants. Animals from the same species have similar appearances. However, there can be differences in structure, size and colouring between the male and the female. This difference is called dimorphism.

Activities 18. Make a list of animals that show sexual dimorphism. 19. Describe the differences between the male and female of some animals.

donkey

female horse - mare

mule

The lion and lioness are examples of dimorphism.

A male peacock uses its colourful tail to attract the female.

When a donkey and a mare mate, the result is a mule. Mules are sterile because donkeys (Equus asinus), and horses (Equus caballus) belong to different species.

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Activities 20. Study the illustrations. Which represent living things? Which characteristics support your decision? A

A

D

C

B

25. Study the cell diagrams. Match each with a name and description.

G F E

H

B

21. Classify these living things as autotrophic or heterotrophic. C A

B

C

D

E

F

22. Copy and complete the chart. Biomolecule

Function

Glucides

Proteins

23. Draw an animal cell with the most important organelles. What structures would transform it into a typical plant cell? Draw them. Include: mitochondria, cytoplasm, cell membrane 24. Test your classmates. Ask questions about the five kingdoms.

40

1. They are long and thin in order to absorb water and mineral salts from the soil. 2. They are shaped like wires with a lot of extensions. They conduct messages around the body.

Lipids

Which kingdoms

D

are made up of have

autotrophs / eukaryotes? no tissues? unicellular and multicellar living things?

3. They have a tale (flagellum) which enables them to swim towards the ovum. 4. They have no nucleus so they have room to transport oxygen in the haemoglobin. – Sperm cell

– Neuron

– Red blood cell

– Root hair cell

26. Complete the table on sexual dimorphism. Animal

Group

Male

Female

lion

mammal

long mane

no mane

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What should you know? Common characteristics of living things

LIVING THINGS

Composition

Cells

Classification and biodiversity

• • • •

3

They are born and they die. They have a similar chemical composition. They are made up of cells. They have three vital functions: nutrition, interaction with the environment, and reproduction.

They are made up of two kinds of substances: • Inorganic substances. Not exclusive to living things: water and mineral salts. • Organic substances. Exclusive to living things: glucides, lipids, proteins and nucleic acids. Cells consist of: • A plasmatic membrane which surrounds the cell. • Cytoplasm or internal matter. It contains the organelles (mitochondria, chloroplasts, etc.). • Genetic material. This controls cell functions. There are various kinds of cells: • Prokaryotic. With no nucleus and no nuclear membrane. • Eukaryotic. With a nucleus and a nuclear membrane. Animal and plant eukaryotic cells are different. Living things may be: • Unicellular. Consisting of one cell. • Multicellular. Consisting of many cells forming tissues, organs and systems. Living things are classified into kingdom, phylum, subphylum, class, order, family, genus and species. There are five kingdoms: • Monera Kingdom: unicellular, prokaryotic living things. They may be autotrophic or heterotrophic. • Protoctist Kingdom: unicellular and multicellular living things. They are eukaryotes and have no tissues. They may be autotrophic or heterotrophic. • Fungi Kingdom: unicellular and multicellular beings. They are eukaryotes and have no tissues. They are heterotrophic. • Plant Kingdom: multicellular eukaryotes. They have tissues and they are autotrophic. • Animal Kingdom: multicellular eukaryotes. They have tissues and they are heterotrophic.

Projects INVESTIGATE: an organisation trying to save the biodiversity of the planet. Give examples of actions taken. WEB TASK: Learn how you can protect the biodiversity.

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UNIT

4

Invertebrates

What do you remember? • What characteristics make the giant squid an invertebrate? • Do you know any invertebrates with … – a soft, porous body? – an elongated body with rings? – a soft body covered by a shell? – an external skeleton?

The giant squid is the largest known invertebrate: 20 m long, 1,000 kg. Its tentacles are more than 15 m long. It lives deep in the ocean: 400 to 1,500 m below the surface.

Content objectives

Key language

In this unit, you will …

Making generalisations

• Recognise the main characteristics of invertebrates

Most sponges live in the sea. Some molluscs have no shell.

• Classify invertebrates into groups

Making impersonal statements

• Describe invertebrate life functions

Their bodies are divided into segments. They are made up of one or two valves.

• Make a model of an invertebrate that can float • Differentiate between bilateral and radial symmetry

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Did you know that...?

Expressing contrast Some are carnivores, but others are herbivores.

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1. What makes up the animal kingdom? The animal kingdom is made up of multicellular, eukaryotic organisms. They are heterotrophic and sensitive to their environment.

How are animals classified? Animals are classified in two groups: • Invertebrates. Animals with no backbone. Some, like worms or jellyfish, have no skeleton. Others, like insects or spiders, have an external skeleton or exoskeleton. • Vertebrates. Animals with a backbone which is part of their internal skeleton or endoskeleton.

Activities 1. What part of a sponge body does the name porifera refer to? 2. Copy the drawing of the sponge. Use arrows to label the flow of water. Show the entry points and the exit point. 3. Talk about cnidaria.

Which

are have can

tentacles? carnivorous? radial symmetry? an opening at the top? a body like a tube? float?

The simplest invertebrates The simplest invertebrate animals are classified into two groups: porifera and cnidaria. Porifera and cnidaria have no organs.

water exits osculum water enters

Porifera Sponges belong to this group. Most live in the sea. Their bodies are full of pores and channels, so water circulates in and out of them. They feed by filtration. Water enters though the central cavity, deposits nutrients, and leaves through a hole called the osculum. Sponges do not move around; they are attached to rocks or coral. Cnidaria There are three different groups of cnidaria: jellyfish, corals and sea anemones. Their main characteristics are: • radial symmetry. • a soft body, with only one opening, the mouth, which is surrounded by tentacles. • a gastrovascular cavity, something like a stomach, connected to the mouth. • Nutrition. Cnidaria are carnivorous: they use their tentacles to capture prey. • Interaction. Most cnidaria live in the sea. Jellyfish can float; corals and sea anemones live fixed to the sea bed. • Reproduction. In their lifetime, cnidaria usually pass through both the polyp and the medusa stages: Polyps reproduce asexually by budding. Jellyfish (medusae) reproduce sexually: there are male and female specimens.

channels

pores Cross-section of a porifera tentacles

polyp

jellyfish

Cnidaria

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2. How do these worms differ? These worms have bilateral symmetry, a soft body, and no skeleton. Annelid bodies are divided into segments. Each segment has a cavity called a coelom. Nematodes have no segments. The most common types of worms are:

PLATYHELMINTHES

ANNELIDS

BODY

BODY

Long, flat, soft. In tapeworms the body is divided into rings. No legs. No respiratory or digestive system.

Soft, cylindrical body divided into segments. Each segment is similar and has the same organs. These repeated segments are called metameres. Tiny appendages on each segment enable movement. Annelids breathe through gills. Exception: earthworms breathe through the skin. clitellum

NEMATODES segments

BODY Soft, cylindrical bodies. No segments or rings. No respiratory system.

The Taenia tapeworm is a parasite that lives in human intestines. It absorbs nutrients directly from its host. Some Taenia species are more than ten metres long.

HABITAT

HABITAT

Water or soil. Some are parasites.

Water or damp places. Many are parasites.

head

Earthworm digestive tube

body wall coelom

setae or hairs

REPRODUCTION

REPRODUCTION

Heterosexual: There are male and females specimens.

Hermaphrodites: They have both male and female sex organs. Platyhelminthes can fertilise themselves.

Cross-section of segment with coelom cavity

HABITAT Water. Some are parasites, for example, leeches.

Activities 4. Make your own table. Annelids Main characteristics

5. Which groups do the animals in the photos belong to? 6. Talk about these worms.

Habitat

Which Example

44

in water? are hermaphrodites? breathe through gills? live parasites?

REPRODUCTION Some annelids are hermaphrodites. Earthworms have larger segments called clitellum where the eggs are deposited.

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3. What are molluscs? Squid, mussels, oysters, slugs and snails are all common molluscs. Most are aquatic: they live in the sea or in fresh water. Garden snails, however, live in damp soil.

What is a mollusc body like?

shell

stomach

Molluscs have these main characteristics: • bilateral symmetry • a soft body divided into three parts: – head which contains sensorial organs and the mouth – body mass with the main organs – muscular foot to move about • The body is covered by a fine membrane, the mantle. This produces a protective shell. The shell is made up of one or two valves. Some species, such as octopi and slugs, have no shell. Others, such as cuttlefish and squid, have an internal shell.

body mass

lung

eyes

head

mouth

foot Garden snail

Mollusc functions • Respiration. Aquatic molluscs breathe through gills. Terrestrial molluscs breathe through lungs. • Nutrition. Some are carnivores. Others are herbivores. • Reproduction. Most are hermaphrodite and oviparous. The larva hatches, goes through metamorphosis and produces an adult individual.

How many groups are there? There are three main groups: • Gastropods: snails, sea snails and slugs. They have a spiral-shaped shell with a single valve. Exception: slugs have no shell. • Bivalves: clams, cockles and mussels. Their shells have two valves. • Cephalopods: squid, cuttlefish and octopi. They have tentacles, but no shell.

Gastropods: slug

Bivalves: mussel

Activities 7. Make your own table for molluscs. Use page 44 as a model. 8. Match the photos to the words. no shell – eyes – foot – garden snail – bivalve – mouth – spiral shell

Cephalopods: squid

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4. What are arthropods? Arthropods are the largest, most varied group of living things: more than one million species. They live in sea water, fresh water and on land. thorax

head

antennae

What is an arthropod body like? The main characteristics of arthropod bodies are: • a segmented body covered by a thick cuticle that acts like an external skeleton or exoskeleton. • a body divided into three parts: head, thorax and abdomen. In some arthropods, the head and thorax are joined to form a cephalothorax. The antennae, eyes and mouth are in the head. The sensorial organs are welldeveloped. The eyes can be simple: ocelli, or compound. • bilateral symmetry • jointed appendages: legs, antennae, wings in insects. The number of legs varies.

wings abdomen

compound eye mouth legs

Wasp

Arthropod functions • Nutrition. Arthropods can be carnivorous, herbivorous or scavengers. • Respiration. They breathe through trachea (terrestrial arthropods) or gills (aquatic arthropods). • Reproduction. Most have male and female sexes which are distinguishable. They are oviparous. Fertilisation is internal. Some hatch as larvae and undergo metamorphosis. As they grow, arthropods shed the old exoskeleton and grow a new one. This is called moulting. Moulting takes place various times throughout an arthropod’s lifetime. In other words, arthropod growth is discontinuous.

Activities 9. Make your own table for arthropods: see page 44. 10. Make generalisations about arthropods. Use pages 46 - 7. Some are ... . Most are ... . Some have ... , but others ... .

METAMORPHOSIS OF A MONARCH BUTTERFLY 1 2

3

1 The female lays eggs. A larva, called a caterpillar, hatches. 2 After a short period of development, the caterpillar changes into a pupa (chrysalis stage). 3 After more changes, the chrysalis breaks open and the butterfly comes out.

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How many groups are there? Groups

Examples

Body / Appendages

Habitat

Crustaceans

lobster, crab

usually 10 legs

aquatic

Myriapods

centipede, scolopendra

worm-like body, many legs

terrestrial

Arachnids

spider, scorpion

8 legs

terrestrial

Insects

butterfly, ant, bee, wasp

6 legs, 2 antennae, 2 or 4 or no wings

terrestrial, some aquatic

Crustacean. Lobster. The front legs have claws for defence.

Myriapod. Scolopendras are fast-moving, venomous and predatory.

abdomen cephalothorax

legs

pedipalp chelicerae

Arachnid. Spider. The cephalothorax has two chelicerae which help the spider eat, and two pedipalps for defence. Spiders have four pairs of legs: eight in all.

Insect. Ants have a strong mouth for chewing and six legs.

Did you know that...? In some cultures, insects are food. You might find these insects in an Indonesian restaurant: fried dragonflies.

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5. What are echinoderms? Echinoderms live on the sea bed. Some live fixed to a surface, but others move slowly about. Examples: sea urchins, starfish and sea cucumbers.

arm

What is the body like? The main characteristics of echinoderms are: • radial symmetry in adults, bilateral symmetry in larvae. • body shape: rounded (sea urchin), cylindrical (sea cucumber) or like a star (starfish). • an internal skeleton made up of plaques. • no separate head, but there is a mouth on the underside.

ambulacral apparatus

Starfish

ambulacral feet

Echinoderm functions • Movement. The ambulacral apparatus, a series of internal tubes filled with water, enables movement. The tubes form ambulacral feet with suckers. • Respiration. Most echinoderms breathe through their skin, using the ambulacral apparatus. Some have simple gills. • Nutrition. They are carnivorous and feed mainly on small crustaceans and molluscs. • Reproduction. Most echinoderms have male and female sexes, but some are hermaphrodite. Fertilisation is external. The larvae can swim and undergo metamorphosis to change into adults.

Did you know that...? Starfish can regenerate body parts or a whole body. All they need is a single leg with part of the central disc.

Activities 11. Can you trace the radial symmetry on the photos? 12. Make your own table for echinoderms: see page 44. 13. How does a starfish feel? And a sea urchin?

How many groups are there?

Echinoedea: sea urchins

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Stelleroidea: starfish

Crinoidea: sea lilies

Holothuroidea: sea cucumbers

Ophiuroidea: ophiura

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Hands on Carrying out an experiment The exoskeleton of an insect is covered with a fine layer of grease or wax. This makes it impermeable. The wax protects insects which live in water, such as the skater (Gerris lacustris). The skater floats on the water surface. If its legs get wet, it cannot take off. Skaters can walk on water without sinking.

Compare the performance of insects with or without impermeable legs

1. Make two identical insect models from card as in the photograph. Body: a rectangle 4 x 6 cm Legs: 5 cm long Fold the ends of the legs so the insects can stand.

2. Melt wax from a candle. Cover the bottom of the legs of only one insect with the wax.

Observe and record the data

3. Place both insects on the surface of the water. Observe carefully, and record your data on a chart like this one. Initially, after two minutes, then after 10 minutes.

It stands on its legs.

It floats initially.

Model with wax

It floats after 2 minutes.

Model without wax

It floats after 10 minutes.

Insect without waxed legs Insect with waxed legs

Interpret the results

4. Does the wax make the paper model impermeable? Activities 14. What would happen to an insect with no wax on its legs? It would float / sink. 15. RESEARCH: Spiders can walk on their webs without sticking. Can you explain this? Think about the experiment above.

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Activities 16. The nautilus lives in a spiral-shaped shell. Inside, the shell is divided into compartments. The animal lives in the largest one. The other compartments are filled with gas, so the shell floats.

20. Identify the photos: annelid or caterpillar. Compare them. The... has, but the... has...

a

a. What group of molluscs does the nautilus belong to? Explain. b. What is the main difference between a nautilus and an octopus?

The animal lives in this compartment

b

Nautilus

17. Copy and label the cnidaria: tentacles, opening, can float, live fixed.

21. Read and label: Tapeworms can be 4 metres long. The bulge in the front of the body is called the head or scolex. It has four suckers and pointed hooks. The thin part below it is called the neck. There are many rings which get bigger as they get older and move farther from the head. Label the drawing: head, suckers, hooks, neck, rings.

18. Which group of invertebrates does each animal belong to?

a

e

c

b

f

d

g

h

22. Name each group of molluscs.

a

b

c

d

19. Study the drawing of the starfish. a. Copy, then label the following parts: arms, ambulacral apparatus, ambulacral feet. b. What do starfish eat? What body mechanisms do they use to eat?

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What should you know?

4

Porifera • The body resembles a sack full of pores and channels. Water circulates through it. • Porifera live attached to a surface. They feed by filtration.

INVERTEBRATES

Cnidaria • They have a soft body and a mouth surrounded by tentacles. There are two body types: polyps which live attached to a surface, alone or in colonies, and jellyfish which float in the sea. • They are carnivorous. Worms • They have a soft body and no skeleton. • The main groups are: – Platyhelminthes: long, flat, soft bodies. – Nematodes: soft, cylindrical bodies, not divided into segments – Annelids: soft, cylindrical body divided into segments Molluscs • They have a soft body divided into three parts: head, body mass and foot. Many have a shell. • They breathe through gills (aquatic species) or through lungs (terrestrial species). • They go through metamorphosis. Arthropods • They have jointed legs and an external skeleton. Their bodies are divided into three parts: head, thorax and abdomen. • They breathe through trachea (terrestrial arthropods) or gills (aquatic arthropods). • They change their outer covering (moult), and some undergo metamorphosis. Echinoderms • They have an internal skeleton made up of plaques under their skin. • They breathe through their skin, using the ambulacral apparatus. Some echinoderms have simple gills. All are carnivorous. • They undergo metamorphosis.

Projects RESEARCH: Find out what crustaceans local fish markets sell. Make a list. WEB TASK: Find out what some spiders eat.

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UNIT

5

Vertebrates

What do you remember? • What is common to all animals? • What are the three vital functions of all living things? • What are the two main groups of animals? How do they differ? • How many groups of vertebrates are there?

Content objectives

Key language

In this unit, you will …

Expressing purpose

• Learn basic characteristics of animals

Aquatic amphibians use lungs to breathe.

• Compare vertebrates and invertebrates

Expressing cause and results

• Recognise the vital functions of vertebrates

Expressing contrast

• Make a scientific drawing

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They undergo metamorphosis. As a result, they lose their gills and develop lungs. A shark’s skin, however, has denticles. All reptiles have legs. However, snakes do not.

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1. What characteristics do vertebrates have? All vertebrates have an endoskeleton with a backbone. The body is made up of a head, a trunk, and many have a tail. Vertebrates have articulated limbs, a well-developed nervous system and bilateral symmetry. head

brain

spinal column

trunk

articulated limbs

Penguins have bilateral symmetry.

Horse

Jellyfish

tail

Spider

Activities 1. Study the photos and classify the animals: vertebrate or invertebrate. 2. Compare the spider and the lion: legs, body, covering... 3. Show the bilateral symmetry of two animals with lines.

Lion

Kangaroo

Tortoise

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2. What are mammals like? head

Most mammals are terrestrial animals. Some are aquatic animals like dolphins, but only one, the bat, can fly.

hair spinal column

ears

trunk

Main body parts tail

• A neck joins the head to the trunk. The tail is an extension of the spinal column. • Mammals have four limbs. Terrestrial mammals have legs, aquatic mammals have fins, and bats have wings. • Mammal bodies are covered with hair or fur which keeps them warm. • Mammals have teeth. The shape of the teeth depends on the food the mammal eats. • Mammals have many glands. The most important ones are the mammary glands. These produce milk.

neck

articulated limbs

Alsatian dog

What functions do mammals have?

Activities

• Respiration. They use lungs to breathe. Aquatic mammals come up to the surface to breathe. • Nutrition. They feed on different things. For example, carnivores eat meat. Insectivores eat insects. Herbivores eat plants. Granivores eat seeds. • Reproduction. Fertilisation takes place internally, and the young grow in the mother’s womb. Mammals are viviparous: they give birth to live young. The babies feed on their mother’s milk. • Interaction. Mammals are homeothermal or warm-blooded: they can keep their body temperature constant.

4. Complete the table. Mammals Physical characteristics Nutrition Respiration Reproduction

5. Compare a human being with another mammal. Make a Venn diagram.

How do the three groups of mammals differ?

Monotremes. Example: platypus. Monotremes are born from eggs. They have a beak, but no teeth.

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Marsupials. Example: kangaroo. Marsupials finish their development inside the mother’s pouch.

Placentals. Example: dolphin. The young develop inside the mother’s body, in the uterus.

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3. What are birds like? wing

barbs rachis

spinal column calamus

Feather legs

• A bird’s body is aerodynamic: adapted for flight. The neck is sometimes very long. • Birds have four limbs: the back limbs are legs, and the front limbs are wings. • A bird’s body is covered with feathers. • Each feather has an axis or rachis. Barbs spread out on each side of the rachis. The calamus joins the feather to the body. • Bird bones are hollow. This makes their body light, so they can fly more easily. • Strong wing muscles are attached to the sternum or keel. • Birds have a horny mandible or beak, but no teeth.

keel

beak

Sea gull

Activities 6. Make your table for birds: see page 54.

What functions do birds have? • Respiration. They use lungs to breathe. The lungs are connected to air sacs which enable them to breathe and to fly. • Reproduction. Birds are oviparous: they lay eggs. The eggs are incubated until the chicks hatch. Fertilisation takes place internally. • Nutrition. The shape of a bird’s beak depends on the food it eats. • Interaction. Birds are homeothermal or warm-blooded.

Buzzard. Strong, curved Swallow. Short beak. beak. It catches its prey It captures insects and tears the flesh. in flight.

neck

Heron. Long, pointed beak. It fishes in shallow water.

7. What characteristics enable birds to fly? 8. Associate each beak with how the bird feeds: opens seeds, fishes, tears its prey. a. strong, curved; b. short, strong; c. long, pointed.

Duck. Wide, flat beak. It filters water to obtain food.

Rooster. Strong, short beak. It feeds on grain which it has to open.

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4. What are reptiles like? Most reptiles, like snakes, crocodiles, lizards and tortoises, are vertebrate terrestial animals, but some spend a lot of time in the water. • Reptiles, except snakes, have four limbs or legs. Snakes have no limbs. • Reptile bodies are covered with hard scales to keep them warm. Adult lizards and snakes shed their skin, but tortoises have a hard shell called a carapace.

spinal column skin with scales

What functions do reptiles have? • Interaction. Reptiles are poikilotherms, or cold-blooded. As a result, they cannot regulate their body temperature. Reptiles are warm or cold depending on the environment. • Respiration. Reptiles use lungs to breathe. • Nutrition. Most reptiles are carnivores. They have teeth to capture their prey. Turtles, however, have beaks. Many snakes have fangs connected to glands that produce poison. • Reproduction. Reptiles are oviparous. The eggs develop inside a sac filled with liquid, called amnion. A hard shell protects the eggs and prevents dehydration. Unlike bird eggs, reptile eggs are not incubated. Some snakes are ovoviviparous, that is, the embryo develops inside an egg that remains inside the female until hatching.

legs Green iguana

Activities 9. Make your table for reptiles: see page 54. 10. What is a carapace like? How does it protect the tortoise?

How many groups of reptiles are there? snake

Snakes. Cobras, vipers, boas and snakes

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chameleon

Lizards. Lizards, iguanas, chameleons

tortoise

Turtles. Tortoises and fresh water turtles

crocodile

Crocodilians. Alligators and crocodiles

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5. What are amphibians like? All amphibians begin life in water, and they always live in wet places. However, the adults are vertebrate terrestrial animals, like frogs, toads, newts and salamanders. • Amphibians have four limbs or legs. Frogs have very strong back legs. • Amphibian skin is moist and has no covering. Some amphibians have glands that produce toxins. • Amphibians are the only vertebrates that undergo metamorphosis. As a result, the adults do not look like the young.

tail moist skin

spinal column

Tiger salamander

legs

THE METAMORPHOSIS OF A FROG

1

2

The female lays eggs in the water and the male fertilises them.

3

4

The tail and gills A tadpole with gills and disappear. Legs develop. a tail emerges from the egg and lives in the water.

The adult frog is a terrestrial animal with lungs and four legs.

What functions do amphibians have? • Interaction. Amphibians are cold-blooded. As a result, they do not usually live in cold places. • Respiration. Adult reptiles use their lungs and skin to breathe. Young frogs, or tadpoles, are aquatic and use gills to breathe. • Nutrition. Most amphibians are carnivores, but at the tadpole stage, they are herbivores. • Reproduction. Most amphibians are oviparous, but salamanders are ovoviviparous. Fertilisation takes place externally in some amphibians and internally in others.

Did you know that...? Some South American tribes use secretions from poisonous frogs to make poison darts.

Activities 11. Test your classmates. Complete the text to ask questions. Example: What do tadpoles use to breathe?

12. Show the life cycle of a frog with drawings. 13. Compare frogs and tadpoles in a chart. 14. Make your table for amphibians: see page 54.

What do ...

use to

breathe? keep moist?

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6. What are fish like?

scales dorsal fin

Fish are aquatic vertebrates. Some live in fresh water and some in salt water. • Fish are fusiform: the body is wider in the middle than at the ends. • Fish limbs are called fins. Each species of fish has different fins, but most have dorsal, pelvic and caudal fins. • Fish are covered with scales. A shark’s skin, however, is covered with small denticles. • The lateral line system is a sensory organ that detects vibrations.

lateral line system caudal fin

anal fin

spinal column operculum

pelvic fin

What functions do fish have? • Interaction. Fish are cold-blooded. As a result, they cannot regulate their body temperature. • Respiration. Fish use gills to obtain oxygen from water. The gills are protected by the operculum or cover. However, sharks and rays have no operculum. • Nutrition. Most fish are carnivores. • Reproduction. Fish are oviparous, and fertilisation takes place externally. However, sharks are ovoviviparous; fertilisation takes place internally.

Activities 15. Make your table for fish: see page 54. 16. Which type of fin enables fish to move forward most?

Did you know that...? Many fish have a swim bladder which fills with air to control buoyancy.

How many groups of fish are there? There are two groups of fish: cartilaginous and bony. ray

Cartilaginous fish, such as sharks or rays. The skeleton is made of cartilage.

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carp

Bony fish, such as carp, hake or salmon. The skeleton is made of bone.

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Hands on Scientific diagrams Scientific diagrams often depict living things. A scientific diagram does not have to be a perfect work of art, but it must... • be realistic. • have the correct proportions. • have realistic colours (if it is coloured). • be labelled. Follow these steps to make a diagram of a fish.

1. Put the fish on a tray. Be sure you can see the parts you want to draw.

2. Observe the shape and size.

3. Fill in the outline with the other parts of the fish: fins, operculum, eye, scales…

First, draw the outline and the main elements: fins, tail…

head

lateral line

dorsal fin

caudal fin

eye

operculum

4. Colour the drawing.

pectoral fin

pelvic fin

5. Label all the parts.

Observe the model carefully. Use the correct colours.

Activities 17. Study the scales on a fish. Make a scientific drawing of their shape and position. 18. Touch a fish from the caudal fin to the head. What does it feel like?

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Activities 19. Which of these are characteristic of animals? a. b. c. d.

25. Copy the diagram, and label the parts of a feather.

They have eukaryotic cells. They are heterotrophic. They have an internal skeleton. They have four limbs.

b.

a.

20. What are the characteristics of vertebrates? 21. Do all animals have bilateral symmetry?

c.

26. Reptiles are poikilotherms. What does this mean?

a. Is this kind of symmetry also internal? b. Are there any vertebrates with no bilateral symmetry?

27. Bats are the only mammals that can fly. Compare bat wings and bird wings. What similarities and differences are there?

22. The blue whale lives in the sea, and spends a lot of time beneath the water. a. Why do whales have to come to the surface? b. Why don’t marine mammals have ears?

28. The photographs show a fish, a mammal and a bird. What characteristics enable them to live in water?

a 23. What kind of bird eats each type of food? I. Meat II. Insects in the water

A

B

III. Grain IV. Insects in wood

C

D

b 24. Write a table and complete it with the characteristics of each vertebrate group. Vertical: Mammals, Birds, Reptiles, Amphibians, Fish Horizontal: Type of limb, Skin covering, Homeotherm/ Poikilotherm, Respiration, Nutrition, Reproduction

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c

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What should you know? ANIMALS

Mammals

VERTEBRATES

Birds

Reptiles

Amphibians

Fish

5

• Animals are multicellular, eukaryotic, and have specialised cells. • They are heterotrophic. They are sensitive to their environment, and they can move. • There are two main types of animals: – Invertebrates have no backbone. – Vertebrates have a backbone. There are five groups: mammals, birds, reptiles, amphibians and fish.

• Mammals have limbs. Terrestrial mammals have legs; aquatic mammals have fins; bats have wings. • Mammals bodies are covered with hair or fur. Mammals are homeothermal. They use their lungs to breathe. They are viviparous. They have mammary glands. Mammals feed on different things.

• Birds are aerodynamic. The back limbs are legs, and the front limbs are wings. A bird’s body is covered with feathers. Its bones are hollow. Birds have a beak. • Birds are homeothermal. They use their lungs to breathe. They are oviparous. Birds feed on different things.

• All reptiles, except snakes, have four legs. Reptile bodies are covered with hard scales. • Reptiles are poikilothermal. They use their lungs to breathe. Most reptiles are oviparous and carnivorous.

• Amphibians have four legs. Amphibian skin is moist, and has no covering. • Amphibians are poikilothermal. They use their lungs and skin to breathe. They undergo metamorphosis. Most are oviparous. Adult amphibians are carnivores.

• Fish are fusiform. The limbs are called fins. Fish are covered with scales. • Fish are poikilotherms. They use their gills to breathe. Most fish are oviparous. Most fish are carnivores.

Projects HYPOTHESIS: Feathers keep birds dry. Test this hypothesis. Place some feathers in water; observe them, and revise your hypothesis. WEB TASK: Find out if the Iberian lynx makes a good pet.

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UNIT

6

The plant and fungi kingdoms

What do you remember? • • • • •

Which characteristics enable you to classify ferns as plants? Which characteristics do all plants have? Name two main differences between plants and animals. Do all plants reproduce in the same way? Why are plants and fungi so important in nature?

Content objectives

Key language

In this unit, you will …

Comparing

• Identify the main characteristics of the plant and fungi kingdoms

Ferns are bigger than mosses. Conifers are the largest group of gymnosperms.

• Recognise plant and fungi organs, shape and functions • Discover how plants and fungi obtain nutrition and reproduce • Learn how to make a classification

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Describing a process When minerals dissolve in water, raw sap is produced.

Making generalisations Most gymnosperms are evergreens. Many angiosperms are deciduous.

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1. What living things make up the plant kingdom? The plant kingdom is made up of multicellular, eukaryotic, autotrophic living things. They cannot move about. All plants: • have roots, stems and leaves. These vary according to the species. • are multicellular: made up of many cells which form tissues. • have eukaryotic cells. These cells have a nucleus and organelles surrounded by membranes. They are surrounded by a cellulose wall. They have chloroplasts which contain chlorophyll. Chlorophyll is necessary for photosynthesis. • are autotrophic beings: they can make their own food through photosynthesis. • live attached to the soil. However, they are able to make some movements. For example, they grow towards light.

How are plants classified?

Activity 1. Classify the plants as in the example. Are they vascular?

No

Yes

Mosses

Ferns, gymnosperms, angiosperms

Do they have flowers?

No

Yes

Plants are classified in two groups: non-flowering and flowering. • Non-flowering plants are simple plants without flowers or seeds. – Mosses. They are small, and non-vascular: they have no conductor vessels. – Ferns. They are bigger than mosses. They are vascular: they have conductor vessels to distribute water and nutrients.

Do they have fruit?

No

Yes

• Flowering plants are more complex, with flowers and seeds. – Gymnosperms. They have seeds inside a false fruit, like a pinecone. – Angiosperms. They have seeds inside a real fruit.

Mosses

Ferns

Gymnosperms: pine

Angiosperms: roses

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2. What are non-flowering plants like? Mosses and ferns are non-flowering plants: • They reproduce by spores. The mature spores are dispersed by the wind. The spores germinate and produce new mosses or ferns. • They grow in damp, shady places. They need a lot of water in order to reproduce.

capsule spores swimming sperm

fertilisation

a

b

zygote

germinating spore

mature gametophytes

Life cycle of a moss

Mosses

Ferns

The main characteristics are: • very small, non-vascular plants. • no true roots, stems or leaves. They fix themselves to the ground by rhizoids. • Instead of leaves, they have small laminas called phyllodes. • Mosses produce spores inside capsules at the end of filaments.

The main characteristics are: • vascular plants. They can be very large. • have roots, stems and leaves. The stem, called a rhizome, grows horizontally in the round. • The leaves are large, and are called fronds. • ferns develop clusters of spores called sorus (plural: sori) on the underside of the fronds.

frond

capsule

filament

root rhizome

sorus phyllodes

spores

rhizoid

Moss

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Fern

spores

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3. What are flowering plants like? There are two main groups: gymnosperms and angiosperms. Both grow seeds in order to reproduce.

Gymnosperms

Angiosperms

• Most are evergreens, like pine trees and sequoias. They have leaves all year. The leaves are normally shaped like needles. • The seeds are not protected by a fruit. • They have small, insignificant flowers. These group together into inflorescences or cones. These cones are male and female.

• Many are deciduous, for example, oak trees. They lose their leaves in winter. • The seeds are enclosed by a fruit. The fruit protects the seeds. It also enables them to be dispersed more easily. • They have brightly coloured flowers. The flowers attract animals and facilitate polinisation.

male cones contain the pollen

flowers

leaves

Gymnosperm: pine tree Angiosperm: oak tree leaves The female cones, called pinecones, contain the seeds, called pine nuts

Activities

fruit

Did you know that...? The largest flower belongs to the species Rafflesia arnoldii. One flower can reach a diameter of 1 m and weigh up to 11 kg.

2. Which characteristics differentiate gymnosperms and angiosperms? 3. Research the plants where you live. Classify them into the four main groups in a chart. Describe their reproduction, and identify them as vascular or non-vascular, with cones or with fruits.

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4. What functions do leaves, stems and roots have?

topside

Plants have three main organs: leaves, stems and roots. blade

Leaves Photosynthesis takes place in leaves. The leaves take in and expel gases from the atmosphere. They eliminate excess water in the form of water vapour. This process is called transpiration.

underside petiole

stomata

apical bud

The main part of a leaf is called the blade. A leaf has a topside and an underside. A petiole joins the leaf to the stem. Gases and water vapour enter the leaf and are expelled through small pores. These pores, stomata, are found on the underside of the leaf.

leaves

node

Stems Plant stems are usually above ground. The stem keeps the plant upright and supports it. It also carries substances to other parts of the plant. Some stems, for example, the potato, accumulate reserves of water and food.

stem main root

Leaves and branches are joined to the stem at nodes. The part of the stem between the nodes is called the internode. Stems grow upwards from the apical bud. Lateral branches grow out of axilliary buds along the stem.

secundary roots

Roots

root cap

Plant roots have two functions: to fix the plant to the ground, and absorb water and minerals. Some roots, for example, carrots and beetroots, accumulate food reserves.

root hairs root cap

The root surface is covered with many tiny hairs which absorb the water and minerals. Each root ends in a root cap.

Venus flytrap

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Did you know that...?

Activities

When the Venus Flytrap plant detects an insect, its leaves close quickly to trap the insect inside.

4. Where do vegetables come from? Make a poster showing the vegetables you eat. Classify them as: leaf, stem, root, rhizome, etc. 5. Draw a plant. Label the main parts.

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Hands on Observation and classification of leaves What is a classification system? A classification system is an organised way of grouping objects into similar categories. Scientists use criteria (rules) to sort the objects into categories. Each category in the classification is labelled. An effective system has multiple levels of increasing detail. Creating a leaf classification system

not needle shape

needle shape

Group A

There are an enormous variety of shapes and sizes of leaves in the plant kingdom. In pairs or groups, use these steps to create your own classification system.

parallel veins

not parallel veins

1. Collect samples. Collect as many different samples of leaves as possible. Remember, pine needles are leaves!

Group B

simple leaves

compound leaves

2. Establish criteria for classifying the samples. a. Separate the leaf samples into two different groups. You must use discriminating and objective criteria so everybody will decide the two different groups, without personal opinions. Look at the diagram to help you. b. Now choose new criteria to separate these groups into two more groups. c. Repeat this process again with the new groups, until all the leaf samples in a particular group have similar characteristics.

smooth edge

Group C

not smooth opposite edge arrangement

Group D

Group E

alternate arrangement

Group F

3. Create a key to explain the classification. a. Write down your selection criteria. For example: Group A: leaves shaped like needles. The key can then be used to classify new leaf samples. b. Test your classification system and key. Ask a classmate to add a new leaf sample to a group. If this is done correctly, you know your classification works.

Activities

A

6. Using your key, classify leaves A and B, into groups. 7. How might you change your criteria for classification if you were sorting leaves for a Maths class?

B

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5. How do plants reproduce? • Asexual reproduction. Only one plant is involved. When you take a cutting of a geranium and replant it, asexual reproduction takes place. • Sexual reproduction. Sexual cells from two different plants join together to produce a new plant. Flowering plants have sexual reproduction.

Main parts of a flower

Taking a cutting of a geranium plant

Geraniums reproduce asexually from cuttings of stems with leaves

Flowers are the reproductive organs of angiosperms and gymnosperms. Flowers have two parts: the reproductive part and the protective part. • Reproductive parts: the stamen (male reproductive part) and the pistil (female part). The ovules are found inside the ovary. During reproduction, the ovules come into contact with the pollen which is produced in the stamen. • Protective parts: the petals, which make up the corolla, and the sepals, which make up the calyx.

corolla (petals)

pendule stigma pollen grains

calyx (sepals) style

anther

ovary filament ovules

Did you know that...? “Bee” orchids (genus Ophrys) have flowers which resemble female bees. When a male insect lands on the flower, the pollen rubs on to it, and the insect flies off.

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Stamen

Pistil

Flower

Activities 8. Study the flower diagram on this page. Identify the reproductive and protective parts of the flower. 9. Research ways that pollen can be carried from flower to flower. Make a list, and give an example of a plant to illustrate each one.

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The reproductive stages Plant reproduction has the following stages: pollination, fertilisation, formation of fruit and seeds, dispersal and germination. 1. Pollination. Pollen from one flower’s anther reaches another flower’s stigma. 2. Fertilisation. Pollen reaches the stigma, penetrates it, and fertilises the ovules inside the ovary.

3. Fruit and seed formation. The fertilised flower is transformed. The corolla and the calyx dry up. The ovary changes into the fruit. The ovules are transformed into seeds inside the fruit. 4. Dispersal. The ripe fruit falls off the plant or releases the seeds. 5. Germination. The seeds fall on the ground and germinate. A small root and shoot grow.

Life cycle of a plant Wind and animals transport pollen from one flower to another

The plant flowers

A new plant grows from each seed

pollen grain

After dispersal, the seed germinates

seed

pollen tube

fruit

ovules

Formation of the seed and fruit Fertilisation takes place inside the ovary

6. Can plants react?

Activities

Plants receive information from the environment, and react to it. There are two types of reaction:

10. Describe the reproductive stages of a plant. Refer to the drawing and text.

• Permanent reactions. These reactions relate to growth. For example, if you place a plant horizontally, the stem will grow and curve towards the light. The roots will grow down into the soil.

In stage 1, pollination … Where does (fruit and seed formation) take place?

• Temporary reactions. The plant returns to its initial position when the change stops. For example, some carnivorous plants close their leaves when an insect lands on them.

11. Study the plants around you. Find examples of permanent reactions.

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sunlight

7. What is plant nutrition? Plants are autotrophic: they produce their own food. They use their leaves, stems and roots to carry out these processes:

carbon dioxide

• Absorption. Plants absorb water and mineral salts from the soil through their roots. When mineral salts dissolve in the water, raw sap is produced.

oxygen

• Transportation. The raw sap travels up the conductor vessels from the roots to the stem and leaves. • Transpiration. Excess water is expelled through the stomata as water vapour. As a result, raw sap goes up into the leaves.

water vapour

elaborated sap is distributed

raw sap travels up

• Photosynthesis. Raw sap is transformed in the leaves into elaborated sap: a mixture of water and organic substances. It contains sugars. Sunlight provides the energy needed for this process. During photosynthesis, the plant absorbs carbon dioxide through its leaves. The leaves then expel oxygen through the stomata. Finally, the elaborated sap is distributed throughout the plant cells by the conductor vessels.

Water and mineral salts

• Respiration. Plants breathe. During respiration, plant leaves take in oxygen from the air and release carbon dioxide. carbon dioxide

oxygen in

F

F respiration

out

carbon dioxide

oxygen in

F

F respiration

out

Activities 12. Draw a diagram of a plant. Indicate the phases of nutrition for each part. 13. Observe these drawings. a. What does each drawing represent? Day or night? b. Do plants breathe and carry out photosynthesis all day? Explain your answers. A

O2

CO2 carbon dioxide

F photosynthesis

B

CO2

F

Daytime: respiration and photosynthesis take place simultaneously. Plants breathe AND carry out photosynthesis.

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O2

oxygen

Nighttime: plants breathe but do NOT carry out photosynthesis.

O2

CO2

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cap

8. What are fungi like? Fungi generally grow in the soil in dark, damp places. The main characteristics of all fungi are: • They can be unicellular or multicellular. However, multicellular fungi do not produce different types of tissues. • The cells are eukaryotic. They have a true nucleus and a rigid cell wall. They are similar to plants, but have no cellulose. • They are heterotrophic: they do not produce their own food. There are two types: saprotrophs and parasites. – Saprotrophs break down food from dead, organic materials. – Parasites feed on other living beings. They cause diseases in plants and human beings. • The body is made up of hyphae which are microscopic filaments. The hyphae group together to form the mycelium, which grows underground. • Fungi reproduce by spores. When the spores are dispersed, they form new hyphae which grow into new fungi.

spores

stalk mycellium

hyphae

Toadstool

Activities 14. Compare fungi and plants. How are they different? How are they the same? 15. Talk about fungi: Which fungi are… …edible? …useful? …parasites? …multi-cellular? …poisonous?

Three groups of fungi Fungi can be classified into three main groups.

Yeasts. Some are parasites. Others are useful. Yeast is useful for making bread, beer, wine.

gills

ring

16. Research mushrooms and toadstools. Make a poster.

Moulds. Multicellular. Some are parasites. Others feed on organic matter and decompose it: bread mould, fruit mould.

Mushrooms. Multicellular. Some are edible. Others are poisonous.

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Activities 17. Can a plant move around? And make movements? Explain your answer, giving examples.

e. Elaborated sap is transported to all parts. f. Photosynthesis takes place in the cells of the green parts of the plant.

18. Study the photos and answer. a. What environments do plants live in? b. How do they carry out nutrition? c. Are plants unicellular or multicellular?

A

B

25. Copy and label the flower diagram.

C

26. Compare mosses and ferns. Complete the chart. Size

Vascular or nonvascular?

Roots, stems, leaves?

Reproduction

Mosses

19. Plants are autotrophic organisms.

Ferns

Can photosynthesis take place in a plant root? Why or why not? 20. Which part of the plant is each of these foods? a. cauliflower d. green bean

b. lettuce e. artichoke

c. carrot f. red pepper

21. Imagine the stem from a white carnation is left in a glass of red ink. a. After some time, the carnation petals turn red. Why does this happen? b. What mechanism allows the liquid to travel up the stem? 22. If a flowerpot is placed in a window, the stem grows in the direction of the light. Is this reaction temporary or permanent?

27. Describe the life cycle of a moss. 28. Why do you think male pine cones are located on the far ends of the branches? 29. Paper is made with cellulose. To obtain the cellulose from trees, they are cut down. a. How could more trees be saved? b. How can you recycle paper? c. How else can you save and reuse paper? 30. Look at the tree trunk. There are pairs of rings. The light area corresponds to springtime, when the tree grows most. The dark corresponds to autumn, when it grows less. To find out a tree’s age, count each pair of light and dark rings. How old is this tree ?

23. Cacti have very small leaves, like thorns. What advantage does this have for the plant? What characteristics of cacti allow them to survive in the desert? 24. Put the stages of plant nutrition in order. a. b. c. d.

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Carbon dioxide enters through the stomata. The raw sap travels from the root to the leaves. Oxygen is released and elaborated sap is formed. The roots absorb water and mineral salts, and raw sap is formed.

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What should you know?

6

Plants are multicellular, autotrophic living things. They live fixed to the soil, but can make some movements.

PLANTS

Functions

Non-flowering plants

FUNGI

Flowering Plants

• Nutrition. There are five stages: absorption of nutrients, transportation, transpiration, photosynthesis and respiration. • Interaction with environment. Plants can respond to changes. • Reproduction. Asexual (only one plant is involved) and sexual (two different plants are involved). • Mosses. They are small, non-vascular plants. They have no true roots stems or leaves. • Ferns. They are vascular plants. They have roots, stems and leaves called fronds. • Gymnosperms. They have seeds, but no fruit. They have small, insignificant flowers. • Angiosperms. The seeds are protected by a fruit. They have colourful flowers. Leaves. They carry out photosynthesis. Gases are exchanged and transpiration takes place through the leaf stomata. Stems. They keep the plant upright and support the plant structure. Roots. They fix the plant in the soil, and absorb water and mineral salts. Flowers. They contain the reproductive system. The main parts are the corolla, calyx, stamen and pistil.

Fungi can be unicellular or multicellular. They have eukaryotic cells. They are heterotrophic. Fungi are made up of hyphae, which group together to form the mycelium. Fungi are classified into: • Yeasts. Unicellular. They are used to make bread, wine, beer… • Moulds. Multicellular. They grow on food products. • Mushrooms and toadstools. Multicellular. Some are edible, others are poisonous.

Projects INVESTIGATE: How is bread made? How was penicillin discovered? What sort of fungi are involved? WEB TASK: Where can you find the tallest tree in the world?

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UNIT

7

The simplest living things

What do you remember? • What do all living things have in common? • What three vital functions do all living things carry out? • What is the chemical composition of all living things? • Where can you find microorganisms?

Content objectives

Key language

In this unit, you will …

Expressing facts

• Identify the main characteristics of microorganisms

Parasites feed off living things. Saprophytes live on decomposing matter.

• Examine the structure and vital functions of bacteria

Describing

• Learn how viruses are structured • Observe microorganisms under the microscope

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Viruses cannot live independently of their host. Algae have no true tissues or organs.

Giving instructions Label each jar. Observe the samples.

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1. What is the Monera kingdom? flagellum

The Monera kingdom contains unicellular, microscopic, prokaryotic organisms. They do not have an organised nucleus. Bacteria belong to the Monera kingdom. They can live almost anywhere. They sometimes form colonies, but each individual cell remains independent. The first living things on Earth, more than 3,500 million years ago, were probably bacteria.

genetic material

cytoplasm

Bacteria nutrition Most bacteria are heterotrophs: they do not produce their own food.

bacteria capsule

• Parasites feed off living things. They cause illnesses like tuberculosis and cholera. • Saprophytes live on dead or decomposing matter. They transform organic substances into inorganic substances. Some saprophytes are useful: lactobacilo is used to make yoghurt. • Symbionts live on the bodies of other living things to provide mutual benefit. They can be found in the digestive system of many mammals. There, intestinal bacteria help with digestion. Some bacteria are autotrophs. For example, cyanobacteria make their own food through photosynthesis.

cell wall plasmatic membrane Bacteria cell structure

Activities 1. Draw a bacteria cell and label it: cell wall, cell membrane, cytoplasm.

Bacteria reproduction

2. Compare bacteria. Complete the chart:

Bacteria generally reproduce by binary fission, producing two daughter cells. Each daughter cell grows, and then divides again.

Nutrition Parasites

Saprophytes

Symbionts

How many groups are there? Bacteria can be classified into four groups by their shape.

Coccus. Spherical

Bacillus. Rod-shaped

Vibrio. Curved-rod shaped

Spirillum. Helical

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2. What is the Protoctist kingdom? The Protoctist kingdom includes unicellular and multicellular living things. They are all eukaryotes and have no tissues. Protozoa and algae are found in this kingdom.

Did you know that...? Plasmodium, which cause malaria, need both a vertebrate and a mosquito to complete their life cycle.

What are protozoa? The main characteristics of protozoa are: • Unicellular. A single cell carries out all the vital functions. • Heterotrophs. They feed on bacteria, organic remains and other microscopic organisms. • They live in both salt water and fresh water. Some protozoa float on water, zooplankton, and are food for aquatic animals. • Some are parasites, and cause illnesses.

How many groups are there? There are four groups of protozoa. They are classified according to the way they move.

blood cell

flagellum

cilia

Flagellates Movement: using a flagellum or tail. Nutrition: some are parasites. Fact: Trypanosoma causes sleeping sickness.

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Ciliates Movement: using cilia: hair-like organs. Nutrition: Some are parasites. Fact: Paramecium is shaped like a slipper. It has two nuclei.

pseudopods

Rhizopods Movement: using pseudopods: projections of cell cytoplasm. Nutrition: Some are parasites, others are not. Fact: Entamoeba histolytica causes dystentery.

plasmodium

Sporozoa No movement. Nutrition: All are parasites. Fact: Plasmodium causes malaria.

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What are algae? The main characteristics of algae are: • Unicellular or multi-cellular. Unicellular algae sometimes form colonies. Each cell can carry out the vital functions. All the cells of multicellular algae look the same and have the same functions. Therefore, algae have no true tissues or organs. • Autotrophs. They contain chlorophyll and other pigments which capture sunlight for photosynthesis. They can be classified by their pigment: green, brown or red. • Some live in salt water and fresh water, but others live on tree trunks or rocks. Some unicellular algae, like diatomea, float on water forming phytoplankton, and are food for aquatic animals. Algae provide food for humans too, for example, ice cream is made from algae. Industrial uses include medicines and fertilisers.

Diatomea. These unicelular algae have a silica shell formed by two interlocking valves.

How many groups are there?

Green algae Colour: mainly green Habitat: on the surface of salt water or fresh water Example: Euglena, Ulva

Did you know that...?

Brown algae Colour: green, yellowish pigment Habitat: salt water, on rocky coasts and on the surface of water. Example: Diatomeas, Sargazos

Red algae Colour: green and red Habitat: deep in warm, still ocean water Example: Coralina

Activities 3. Compare protoctists and monera. Examples:

Many acuatic animals feed on zooplankton and phytoplankton. Example: the blue whale

... live in ... . ... are autotrophs, but ... are ... . 4. Describe how each group of protozoa move. Example: ... move using... . ...do not move. 5. What do algae have in common with plants? 6. Compare protozoa and algae. Draw a Venn diagram.

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3. What are viruses? Viruses are not cells, so they are not really living things. They cannot carry out any vital functions by themselves. They infect living cells, and then they can reproduce. They are always obligate parasites: they cannot live independently of their host.

What is a virus like? The main characteristics of viruses are: • Extremely small. They can only be seen through an electron microscope. • Unable to move. • Extensive habitat. They are found on the ground, in the air and in water.

Flu virus seen under an electron microscope

Nucleic acid. Genetic material inside the capsid Capsid. A protein shell. It can have different shapes.

Viral envelope. It covers the capsid. Only some viruses like influenza or HIV viruses have one.

Virus infection process 1. The virus enters 2. Reproduction: viruses use the infected 3. The viral components 4. New viruses the cell. cell to make the viral components. assemble. leave the cell.

cell membrane

Infected cell

Did you know that...? Rabies, a fatal disease in humans, is caused by a virus. Louis Pasteur and Emile Roux developed the first rabies vaccination in 1885.

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Activities 7. Which vital function do viruses share with other living things? 8. Draw and label a virus.

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4. What are infectious diseases? An infectious disease occurs when a pathogenic microorganism invades a living thing, and causes an illness.

respiratory system

Microorganisms reproduce very quickly inside the body. However, the effects of an infection are not immediate. First, there is an incubation period. Then, various symptoms of the illness are observed, for example, a high temperature. When microorganisms are transmitted from a sick person to a healthy one, contagion occurs. Transmission can take place in many ways: see the diagram and chart.

contact with the skin

digestive system

Symptoms are the effects that a disease has on the body, and can be observed. Vectors are insects that carry a disease from one person to another. Mosquitos (Anopheles) can carry Plasmodium which causes malaria, if they bite an infected person.

Some illnesses caused by microorganisms Illness

Microorganism

Cold

virus

AIDS

virus

Pneumonia

bacteria

Transmitted through

the air

Symptoms sexual contact

stuffed up nose, sneezing, high temperature, coughing

general sexual and blood weakness, contact weakened defences

the air

fever, coughing, pulmonary infection How microorganisms enter the body

Salmonellosis

bacteria

spoiled food

high temperature, nausea, vomiting, diarrhoea

contaminated water

nausea, vomiting, stomachache, severe diarrhoea

Activities Cholera

protozoan

Malaria

protozoan

Athlete’s foot

microscopic fungus

the bite of the headache, female Anopheles intermittent mosquito vomiting, fever physical contact through the skin

itching and cracked skin, scaly skin between the toes

9. Use the diagram and chart to classify the entry points for each illness. Copy the diagram and label it with the illneses. 10. Choose two more common illnesses. Copy the chart headings and complete them for both illnesses.

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Hands on Taking and classifying samples. Observing microorganisms Scientists obtain data from nature by collecting samples. They do this for different reasons: • To compare. For example, on farms, blood samples are taken from animals. These are compared to check the animals’ health. Compare two water samples. Then classify the microscopic living things in the water.

• To classify. Classification helps scientists to organise and understand the natural world.

water with leaves and soil tap water

puddle water

1. Take the samples. Put water from a puddle into a glass jar with a screw top. Alternative: put water in a bowl and mix it with some soil and dried leaves. Let it rest for a few days. Put some tap water into another clean jar. Label each jar.

bowl

2. Observe the samples. Using a pipette, put three drops of puddle water onto a microscope slide. Include a fragment of vegetation or clay. Put three drops of clean water onto another slide. Look at the puddle water through the microscope. First observe it with low magnification, then increase it. Study all parts of the slide for a few minutes. Repeat the process with the tap water.

Navicula

Paramecium Colpidium Phyllodinea

Vorticella

3. Identify the living things. Look at drawings of freshwater microscopic organisms to recognise the samples under the microscope.

Scenedesmus Euglena

4. Classify the living things. Can you classify them into groups?

Cosmarium

Activities 11. Did you see any microorganisms in the tap water? Did that surprise you? Why or why not?

14. Compare vaccines and antibiotics. See page 81. Make a Venn diagram.

12. Did you identify any living things in the puddle water? Draw and label them. Remember to write down the microscope magnification.

15. Can antibiotics cure a cold? See page 81. Explain your answer.

13. Would you drink puddle water? Why or why not?

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16. How does intestinal flora help human beings? See page 81.

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5. How can you fight infectious diseases? You can protect yourself from infection in several ways: • Personal hygiene: wash your hands before eating. • Eat and drink only fresh food and drinks.

Did you know that...?

Vaccines A vaccine contains dead or weakened microorganisms from a specific illness. These microorganisms cannot produce the illness, but they can protect against it.

Penicillin was first discovered by Alexander Fleming. It was later developed as an antibiotic. Penicillin has saved millions of lives.

Vaccines teach the body how to fight an illness. Therefore vaccination is a preventive measure. Your body can fight against microorganisms if it is exposed to them. Most vaccines protect the body indefinitely. Others require a booster dose, another dose, later on.

Antibiotics Antibiotics are produced by certain bacteria and fungi. They prevent the microorganisms that cause illnesses from growing. Antibiotics are curative measures and must always be prescribed by a doctor. They cannot fight illnesses caused by viruses.

6. Are all microorganisms harmful? All viruses are pathogenic. They are parasites that cause illnesses. A few bacteria, protozoa or microscopic fungi are pathogenic.

• Intestinal flora are bacteria that live in human and animal digestive systems. They are useful because they produce vitamins.

Many microorganisms are beneficial:

• Other bacteria are used to obtain antibiotics.

Decomposer microorganisms transform dead animals and plants into inorganic substances. Some are harmful.

Plankton is the primary food for many aquatic animals.

Some bacteria are used to make food, like cheese.

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Activities 17. Look at the drawings of a bacteria and a virus. a. Label them. What characteristics helped you? b. What do these organisms have in common?

a

b

h

a b c

a. What type of living things cause red tide?

f e

22. Investigate. Red tide is a natural phenomenon. It is caused by an accumulation of living things. Red tide affects the world’s coasts, especially in spring and summer. Each year it causes the death of many fish, shellfish, molluscs, mussels, oysters, cockles and other marine bivalves.

i

g d

b. How do you think the marine animals become infected? c. Can red tide affect people? Why or why not?

18. What type of organism or structure, 1-3, corresponds to each description? a. They are not really cells; they are obligate parasites. b. Autotrophs or heterotrophs with prokaryotic cells. c. Heterotrophous, eukaryotic, unicellular organisms.

1

2

HIV virus (0,11 mm)

Intestinal bacteria (1 ␮m)

a. Are these bacteria autotrophs or heterotrophs? b. Where do they obtain their nutrients? 24. Look at the protozoa in photos A-D.

3

A

B

C

D

Paramecium (20 ␮m)

19. Microorganisms are microscopic living beings. They are measured in micrometres: one millionth of a metre, or one thousandth of a millimetre (␮m). a. How big, in millimetres, is each microorganism in the picture in activity 18? b. Classify each microorganism: eukaryotic or prokaryotic. c. Which of these microorganisms is not considered a living thing? d. What makes prokaryotic microorganisms different from eukaryotic microorganisms? 20. Unlike certain bacteria and pathogenic protozoa, cyanbacteria and unicellular algae do not produce diseases. Why do you think this is? 21. Compare bacteria, protozoa and algae: cell type, nutrition and habitat. Create a table.

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23. Many bacteria live symbiotically inside the digestive tract of herbivorous animals, like the giraffe, elephant or cow.

What type of structures enables each to move? 25. Cavities in teeth are produced by microorganisms like streptococcus and lactobacillus. a. What type of microorganism are they? b. Are cavities considered an infectious disease? Why or why not? c. What is the best way to prevent cavities? 26. Research beneficial microorganisms in the food industry. Display your results in a poster.

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MICROORGANISMS

What should you know? Monera Kingdom

The Monera kingdom includes unicellular, microscopic, prokaryotic organisms. Bacteria belong to the Monera kingdom. They are classified according to shape: • Coccus: Spherical • Bacillus: Rod-shaped • Vibrio: Curved-rod shaped • Spirillum: Helical

Protoctist Kingdom

The Protoctist kingdom includes unicellular and multicellular living things. They are all eukaryotes and have no tissues. They are generally very small and include: • Protozoa are unicellular. They are heterotrophs. They live in both salt and fresh water. Some are parasites. They are classified by the way they move: flagellates, ciliates, rhizopods and sporozoa. • Algae may be unicellular or multicellular. They are autotrophs. They sometimes form colonies. They live in salt and fresh water. Algae are classified as green, brown and red.

7

Microorganisms can be harmful or beneficial. Harmful microorganisms: A few microorganisms cause illnesses. Contagion occurs when microorganisms are transmitted from a sick person to a healthy one.

VIRUSES

Microorganisms

Beneficial microorganisms: • Decomposer microorganisms • Plankton • Intestinal flora • Some are used to make food • Some are used to obtain antibiotics and other medicines.

Viruses are extremely small. They are not cells, so they are not true living things. They are obligate parasites, that is, they cannot live without the host. They consist of a capsid, an external shell and nucleic acid.

Projects EXPERIMENT: Put moist bread in a plastic box. Observe the changes after a few days. What causes them? WEB TASK: Find out about friendly and unfriendly microbes.

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Rock stars... Stereoscopic microscopes illuminate solid objects from above. They are used to obtain magnified, three-dimensional images. They are very useful for studying rocks. Images from a stereoscopic microscope

eyepiece

A

tube fine focusing knob

B light source

coarse focusing knob

stage arm (limb)

C

stand

1. Match these rocks to their corresponding image above.

1

2

3

limestone

granite 2. Describe each rock sample. For example: Granite

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is

black/ white /grey/ reddish / cream. heterogeneous / homogeneous. smooth / rough / sandy.

sandstone

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and instruments There are many different meteorological instruments used to study the Earth’s atmosphere and weather. For example:

A thermometer measures temperature.

A hygrometer measures humidity in the air.

A rain gauge or pluviometer measures rainfall.

3. Look at these photos. What do you think the weather is like in each place?

A

B

The Sahara Desert

The North Pole

C

D

A rain forest

A deciduous wood

4. Match each text to its corresponding photo. 1 Temperature: high

Precipitation: very abundant Humidity: very high.

3 Temperature: very low

Precipitation: very abundant Humidity: very high

2 Temperature: extremely high.

5. Say what the weather is like where you live. Where I live the temperature is...

Precipitation: very low. Humidity: very low.

4 Temperature: medium

Precipitation: abundant Humidity: high

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UNIT

8

The Earth’s atmosphere

What do you remember? • What elements can you see in the photo? Describe them. • In which part of our planet do these phenomena form? • What other atmospheric phenomena do you know? • Air is a mixture of gases. Which are the most abundant? • Is the composition of air the same at sea level as at the top of a very high mountain?

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Content objectives

Key language

In this unit, you will …

Expressing amounts

• Examine the origin and composition of the atmosphere • Discover how living things affect the composition of the atmosphere • Analyse how wind, clouds and precipitation are formed • Study the effects of living things on atmosphere and climate • Make and use a meteorological instrument

The Earth’s atmosphere is about 800 km high. The density of air is about 1kg/m3.

Comparing The ionosphere is the highest and the thickest layer. The higher the altitude, the lower the density of air. The higher a place is, the colder and wetter it will be.

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1. What do we know about the atmosphere? The atmosphere is made up of gases in different proportions. Nitrogen and oxygen are the most abundant. The atmosphere was very different 4,600 million years ago. • The primitive atmosphere was made up of water vapour, carbon dioxide, nitrogen, hydrogen, ammonia, methane and other oxides, but no oxygen. The first living beings (bacteria), produced oxygen by photosynthesis. Molecules formed when chemical reactions took place between some gases. These molecules fell to Earth with rain. • The present atmosphere is made up of 78 % nitrogen, 21 % oxygen, 1 % carbon dioxide, water vapour, and other gases, such as argon. Much later, the ozone layer was formed from oxygen. The ozone layer protects life from harmful radiation from the Sun.

The layers of the atmosphere There are four layers. The Earth’s atmosphere is about 800 km high and is held in place by the Earth’s gravity. The separation in layers is caused by variation in temperature with respect to altitude.

Composition of the air Nitrogen (N2). Colourless. Odourless. 78 % of air

Oxygen (O2). Colourless. Almost all living creatures breathe it. 21 % of air.

Other gases: 1 % Argon (Ar). Ozone (O3) Water vapour Carbon dioxide (CO2) Necessary for photosynthesis

Activity 1. Why does oxygen in the atmosphere make it suitable for life? And carbon dioxide? And water?

500 km

Ionosphere. The highest and the thickest layer. Its temperature increases to 1,000 °C due to X-rays and gamma rays from the Sun. 400 km

Comets appear here.

A LT I T U D E

80 km Mesosphere. About 40 km thick. It contains clouds of ice and dust. 300 km

40 km

200 km

Stratosphere. About 30 km thick. There is an increase in temperature from −70 °C at its lower limit to 0 °C at its higher limit. The ozone layer is here.

Ozonosphere

10 km

100 km 80 km

Troposphere. Very thin, but contains 80 % of the total mass of the atmosphere. This is where meteorological phenomena occur.

40 km 10 km 0 km

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2. What makes up the weather? Weather describes the state of atmospheric conditions at a certain place, over a short period of time. Weather conditions include: • Humidity. The concentration of water vapour in the atmosphere. • Clouds. Formed when rising air cools. • Precipitation. Water that falls to the ground: rain, snow and hail. • Temperature. How hot or cold the air is. • Wind. Movements of air.

Did you know that...? Weather spreads the Sun’s heat around the Earth. Without weather, the tropics would get hotter and the Poles would get colder, until there was no life on Earth.

Atmospheric pressure Air has weight. The pressure it exerts on a surface is called atmospheric pressure. It is caused by gravity, and is measured in millibars (mb). In the 17th century, the Italian scientist, Torricelli, proved that atmospheric pressure decreases with altitude. Therefore, at sea level, the pressure is higher than at the top of a mountain.

L

The density of air on the Earth’s surface is about 1 kg/m3. This means that 1 m3 weighs 1 kg. The higher the altitude, the lower the density of air.

Predicting the weather

996

H

0 1 00

Air moves from high pressure areas to low pressure areas. This enables weather forecasters to predict the weather. Air moves because the Sun heats it. Hot air rises and the colder surrounding air moves in to take its place. • Low pressure area. Air moves from the sea towards a land mass. It brings humidity with it. Clouds form and precipitations occur.

On weather maps, lines called isobars connect points with the same atmospheric pressure. Look at this example. H = high pressure L = low pressure

• High pressure area. Air moves from a land mass towards the sea. There are no clouds and the sun shines.

1008 1 016

H

1 000

12 10

992

10 04

L

988 980 984

Activities

996

2. What is atmospheric pressure? 3. Does the atmospheric pressure at the Poles have the same value as at the Equator? Explain.

The rotation of the Earth also makes air move in spirals.

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3. What factors affect climate? Climate describes the characteristic pattern of weather in an area, over a long period of time. Factors affecting climate are: • Latitude. How far north or south a place is from the Equator. At the Equator, solar energy is concentrated and causes high temperatures. Towards the north and south, solar energy is more spread out and causes cold temperatures. • Altitude. The height above sea level. The higher a place is, the colder it will be. • Distance from the sea. – Sea water heats up slowly and cools down slowly. In winter the sea releases heat, keeping coastal areas warmer. – Land heats up quickly and cools down quickly. In summer, cold sea keeps coastal areas cooler. • Ocean currents. – Warm ocean currents flow up from the tropics to the poles and warm up surrounding areas, especially in winter. – Cold ocean currents can lower temperatures in an area.

Activities 4. Look at the four factors that affect climate. Can you define how these affect the climate in your part of the country? 5. What will the weather probably be like if you are looking at cirrus clouds? And if you are looking at cumulonimbus clouds?

Clouds and precipitation • Rain occurs when condensation makes large, heavy droplets which fall to Earth. Snow and hail occur when the water vapour in the air freezes. • Clouds form when rising air cools. Some of the water vapour molecules in the air condense to form cloud droplets or ice crystals. There are three basic types of clouds: cirrus, cumulus and stratus. There are many variations of these.

Cirrus. High, thin clouds. These form above 6,000 m. They normally mean fair weather.

Cumulus. Like cotton wool. They form at about 1000 m. They can develop into cumulonimbus: thunder clouds.

Coastal areas have milder weather than inland areas.

Stratus clouds. Low, horizontal clouds. These normally cover most of the sky. Usually no precipitation falls.

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4. What is meteorology?

1 024

1 008

H 1 024

1 00 0

1 016

Meteorology is the study of different atmospheric variables to make weather predictions. Meteorologists collect information about temperature, precipitation, wind, the humidity of the air, atmospheric pressure and clouds.

1 016 1 008 1 016

1 02 4

Meteostat photo

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Meteorological map

Map with weather symbols

The most important meteorological instruments A thermometer measures temperature.

A barometer measures atmospheric pressure.

Activities

A rain gauge / pluviometer measures the amount of rainfall per square metre.

A hygrometer measures the humidity in the air.

6. You hear this report on the radio: Wind speeds were 95 kilometers an hour and 200 litres of rain fell per square metre. What instruments were used to collect this information? 7. Copy and complete. Metereological instrument anemometer

An anemometer measures wind speed.

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A weather vane shows the direction the wind is coming from.

barometer

Measures/ Shows

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Hands on Observing the weather Make and use an anemometer to measure wind speed An anemometer measures wind speed. Remember that wind is simply moving air. Materials

– A pencil with an eraser end – A drawing pin – A plastic plate

– One coloured plastic cup – Three white plastic cups – A stapler

1. a. Staple each cup to the plate so that they are spread out equally. b. Pin the plate to the eraser on the end of the pencil. Make sure the plate can spin round easily. c. Take your anemometer outside.

2. Watch the wind blow the cups around. Count the number of times the coloured cup passes in one minute. (Revolutions per minute = RPM)

3. Record the wind speed for one week. At the same time, observe the weather for each day. Record if it is fair or unstable.

4. Interpret the results Can you prove or disprove the following hypothesis using your results? High wind speed is directly related to unstable weather.

How to calculate the wind speed First, calculate the circumference (in metres) of the circle made by the rotating paper cups. Multiply the RPM value by the circumference of the circle. This gives you the approximate wind speed in metres per minute.

Activities 8. How cloudy is it when the air pressure is lowest / highest? 9. What kind of wind is associated with rain?

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5. How do humans impact on the atmosphere? Human activities cause atmospheric pollution: the release of harmful substances called pollutants into the atmosphere.

think that air pollution is causing the Earth’s surface to heat up.

Most pollutants are gases: sulphur dioxide, carbon dioxide and nitrogen oxide. They are produced by combustion from motor vehicles, aeroplanes, by burning fossil fuels, and from industrial activities.

Acid rain

Air pollutants can also be particles of liquid and solid molecules: ash from forest fires, black smoke, dust and soot. Pollulants in the air can cause: respiratory system irritation, eye irritation, increase in asthmatic processes, headaches.

Global warming In the last century, our atmosphere has warmed between 0.5 and 0.9 °C on average. Some scientists

Rain is naturally slightly acidic due to carbon dioxide dissolved in it. Pollutants such as sulphur dioxide and nitrogen oxide, form acids when mixed with the rain.

The hole in the ozone layer Ozone exists throughout the atmosphere, mainly concentrated in the stratosphere. Ozone is being destroyed by air pollution. Chemicals called chlorofluorocarbons (CFCs) used in aerosols and refrigerators escape into the atmosphere. They react with ozone and destroy it. Harmful solar radiation may enter through this hole.

Human activities that pollute the atmosphere Human activity

Pollutant

Consequences

gases used in aerosols, air conditioners

CFC gases

Reduces the amount of gas in the ozone layer so more ultraviolet radiation reaches the Earth. Skin cancer results.

particles released from burning coal and other fuels

soot

Cities are dirtier. Buildings are damaged. Can cause lung diseases.

burning fossil fuels: coal, petrol

carbon dioxide (CO2)

Global warming: tropical cyclones, polar ice melts, sea levels rise, severe droughts

burning gasoline

sulphur and nitrate dioxides

Acid rain: damages buildings, vegetation and harms herbivorous animals.

The hole in the ozone layer allows in harmful UV rays. These cause sunburn.

Air contamination from industry Acid rain damages this statue.

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6. What is the greenhouse effect? The greenhouse effect is a natural phenomenon. It is essential for keeping the temperatures on Earth suitable for life.

sunlight enters the ground and air get hotter

The atmosphere absorbs a great amount of solar radiation. CO2 in the atmosphere acts like the glass walls of a greenhouse. It traps the heat and prevents it from returning into space. In this way the Earth does not lose too much heat. If there were no atmosphere, our planet would be much colder.

The increase of carbon dioxide The amount of carbon dioxide in the atmosphere has gradually increased over the last 200 years. Carbon dioxide is produced when fossil fuels are burned; by living things breathing; by fires, and by erupting volcanoes.

Greenhouse made of glass

The Sun heats the air

Some CO2 is dissolved in the oceans and absorbed by growing plants. Unfortunately, people are destroying plants and burning more and more fossil fuels. This means more carbon dioxide is produced. An increase in carbon dioxide means more heat is trapped. Therefore the average temperature of the Earth is increasing.

atmosphere traps the heat

Protecting the atmosphere When pollution is reduced, global warming, the hole in the ozone layer and acid rain are also reduced. By saving energy, the atmosphere will improve and our health will be much better. You are part of the solution. • use hot water carefully: do not waste it • turn off unnecessary heating and electrical devices • travel by public transport, by bike or on foot • avoid aerosols with CFCs • recycle paper, plastic and glass • plant trees

The greenhouse effect

Activities 10. Talk about pollutants. Where

does (carbon dioxide) do (CFC gases)

What damage

does it do they

come from?

cause?

11. Survey. Ask your classmates: Do you protect the atmosphere? Do you recycle paper? Etc.

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Activities 12. Study the map and answer the questions. a. Is cloud and precipitation more likely in Spain or in the UK?

18. Indicate the meteorological role of each instrument and what it measures.

b. What will the weather be like in Spain? c. Where is the low atmospheric pressure coming from? Central Europe or the Iberian Peninsula? d. Copy the map. Use arrows to show the wind direction.

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19. Explain the differences between the primitive atmosphere and the Earth’s atmosphere today. 20. Look at the table. It shows the atmospheric pressure at different times. 12:00

Time

H

14:00

16:00

18:00

Atmospheric 1 020 mb 1 016 mb 1 010 mb 1 007 mb pressure

13. Why do mountain climbers carry oxygen tanks to climb Mt. Everest? 14. What are the five principal components of air? For each one indicate:

a. Is the atmospheric pressure increasing or decreasing? b. Is there a possibility of high pressure or low pressure? c. Will there be a high or low chance of clouds?

a. its proportion 21. Label the maps: weather map or isobar contour map.

b. its origin c. if it has a role in an important process.

Do the two maps show the same weather? Explain.

15. Investigate. Ozone is very scarce, but very important. Explain why it is important. Tell how it can be beneficial and harmful. 16. Draw a greenhouse. Explain what the greenhouse effect is and how it works.

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17. Copy and complete with information about the layers in the Earth’s atmosphere. Approximate thickness Troposphere Stratosphere Mesosphere Ionosphere

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Description of the layer

22. Give three reasons why the atmosphere is essential for life. Use these ideas: a. Sun’s radiation b. gases and living things c. control of Earth’s temperature

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What should you know?

Climate

The average weather over a long period of time.

Human impact

Human activity creates substances that pollute the atmosphere: An increase in carbon dioxide produces the greenhouse effect, which causes climate change. • CFC gases eliminate the ozone from the stratosphere. • Sulphuric oxide and nitrogen oxide cause acid rain. • Soot pollutes the air and creates health problems.

1 024

Studied by meteorologists who measure temperature, precipitation, atmospheric pressure, winds, and humidity. Weather forecasts are based on this information and show it in: • Pressure / isobar contour maps and weather symbol maps Air moves from high pressure areas to low pressure areas. When air cools, the humidity can condensate or freeze, forming clouds and precipitation.

H 1 024 1 016 1 008

1 02 4 1 016

Changes in the atmosphere

The primitive atmosphere contained no oxygen. It underwent several changes: • Water formed the hydrosphere. Carbon dioxide was instrumental in photosynthesis. Photosynthesis increased the amount of oxygen. 1 008

THE ATMOSPHERE

Origin

The atmosphere is composed of air. Air is a mix of gases: • 78 % nitrogen, 21 % oxygen, 1 % other gases • Variable quantities of water vapour The atmosphere is divided into layers: • Ionosphere: The outermost layer. It extends to 500 km above the Earth. • Mesosphere: 40 to 80 km above the Earth. • Stratosphere: Between 10 and 40 km above the Earth. It contains the ozonosphere. • Troposphere: From the Earth’s surface to 10 km above the Earth. Meteorological phenomena occur here.

1 016

Composition and structure

8

L

Projects PROJECT: Weather maps. Collect the weather maps from a newspaper during one whole week. Stick them onto a chart. Write the weather each day next to each map. WEBTASK: You are planning a trip to London. What is the weather like today?

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UNIT

9

The hydrosphere

What do you remember? Look at the picture and answer the questions. • Where can water be found on our planet? • How is sea water different to water in rivers and lakes? • What is the water cycle? Can you describe it? • Why is it important not to waste water? • Do you know some easy ways to save water?

Content objectives

Key language

In this unit you will ...

Expressing amounts

• Find out how water is distributed on Earth

68.7 % occurs in the form of ice and snow.

• Learn about the properties of water

Describing

• Learn about ocean movement: waves, currents and tides

Water is attracted to other water. Water is a powerful solvent.

• Describe the water cycle

Expressing direction

• Identify uses of water and causes of water pollution

Water filters into the ground. Currents move through the sea. Waves transport sand along the coast.

• Study the effects of temperature on condensation

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1. Where is there water on Earth? There is salt water and fresh water on Earth.

Distribution of water on Earth

WATER

97% of the water on Earth is salt water. It is found in the oceans. 3% of the water on Earth is fresh water.

Total water on Earth

Salt water 97 %

Fresh water is found in: 68.7% is ice and snow from glaciers or at the North and South Poles. 30.1% is groundwater: water below the Earth’s surface. 0.9% is in the atmosphere, in living things, etc. 0.3% is surface fresh water. SURFACE FRESH WATER

FRESH WATER

Fresh water 3 %

These small squares represent all the water in the hydrosphere.

Fresh water distribution 0.9% other

0.3% fresh water

68.7% ice and snow

30.1% ground water

Surface fresh water is found in: 87% is found in lakes. 11% is found in swamps. 2% is found in rivers: it is fit for human consumption.

Surface fresh water distribution rivers 2% swamps 11% lakes 87%

Activities 1. How much water is there for human consumption on Earth? Explain. 2. Represent the pie chart information in two bar graphs.

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2. What are the properties of water? Water is a substance with unique properties. It plays an important part in the processes that occur on the Earth’s surface and is essential to living beings. Water is made up of molecules. Each molecule of water is made up of one atom of oxygen and two atoms of hydrogen. At room temperature the molecules can move about freely: water flows. The main properties of water are:

Did you know that...? Water covers 75% of the surface of our planet. This characteristic is unique in the solar system.There is water on other planets, but it is never found in a liquid state nor in such huge quantities.

• A powerful solvent. It dissolves many components of rock. When water evaporates, it leaves deposits of mineral salts. • Absorbs heat. Water moderates the Earth’s climate by absorbing heat in summer and emitting heat in winter. • Cohesion and adhesion. Water is attracted to water: this is called cohesion. Water sticks to itself, it can travel throughs vessels in plants to transport food to the leaves. Water transports substances throughout the bodies of living things. Water molecules are also attracted to other materials: this is called adhesion. As a result, water wets surfaces such as soil and rocks.

PACIFIC OCEAN

Anomalous dilation. When water freezes, it dilates or increases in volume. As a result, the volume of ice is greater than the same mass of water in liquid form.

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3. What are the properties of sea water? Sea water has special properties: • It is salty. Each litre contains about 35 grams of dissolved salts. • It contains dissolved gases: mainly nitrogen, oxygen and carbon dioxide. These gases are dissolved in the water by two processes:

Salts dissolved in sea water chlorides 87%

– the movement of the waves which mixes water with air. – the activity of aquatic beings. Oxygen is produced by the photosynthesis of aquatic plants; living things breathe out carbon dioxide. • The temperature of salt water varies with depth. At the sea surface, the temperature is higher. In the deepest zones, the temperature of the water is lower: between 4ºC and ⫺2ºC.

others 2% sulphates 11%

Movements produced in the oceans Ocean waters move in three ways: waves, currents and tides. • Waves occur on the surface. They are caused by the wind. Waves mix water with the air above the surface, dissolving a lot of oxygen in this zone. Movement of gases occurs from the atmosphere into the oceans, and from the oceans into the atmosphere. Wave action causes cliff erosion and creates beaches. Waves transport sand and mud along the coast and out to sea. • Ocean currents are masses of water which move like rivers through the sea. The currents are produced by wind, differences in temperature, and differences in salinity. • Tides are the periodic rise and fall of the sea level. They are caused by the gravitational attraction of the Moon and, to a lesser extent, the Sun.

Wave action causes rock erosion.

Activities 3. Look up the following terms: solvent, evaporation, cohesion, anomalous dilation and adhesion. 4. Think about cohesion and adhesion. Why are these properties so important for living things? 5. Is there more oxygen dissolved in sea water near the surface or in the deep, darker zones? Explain. 6. Why do you think sea water in warm areas contains more salt than sea water in cold areas?

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4. Where is fresh water found? Fresh water is found on the continents. It contains much less salt than sea water. It is found in different forms: lakes, rivers, torrents, underground rivers, pools and glaciers. groundwater

snow from the mountain tops stream river

wetlands

lake lagoon

Streams or torrents are water courses fed by rain. The flow of water varies a lot from season to season. Wetlands are areas of marshlands and swamps where the ground is inundated all year round. Glaciers are formed from the accumulation of snow on mountain tops. Rivers are permanent water courses. The River Nile is the longest river in the world. Groundwater is water located beneath the ground surface. Lakes are bodies of water of different sizes surrounded by land. Example: Lake Victoria, Africa.

River valley

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Groundwater in a cave

Activities 7. Copy the diagram and label the bodies of fresh water. Which bodies of fresh water can you find where you live? 8. Look out your window. Draw and label the water cycle processes you observe.

Lake

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5. What is the water cycle? The water cycle is the movement of water on, above and below the surface of the Earth. It consists of the following processes: evaporation, evapotranspiration, condensation, precipitation, surface runoff and infiltration. • Evaporation. Liquid water changes to a gas (water vapour). Water passes from the hydrosphere to the atmosphere. • Evapotranspiration. Water evaporates into the atmosphere from the leaves and stems of plants. • Condensation. Water vapour changes to liquid, forming clouds and dew. • Precipitation. Water in the clouds falls to the ground as rain, snow or hail. • Surface runoff. Surface water moves across the land and forms rivers and streams. • Infiltration. Surface water filters into the ground. This occurs more easily if the ground is porous.

condensation in the form of clouds

water vapour

precipitation

clouds ent of m e v mo

precipitation evaporation

surface runoff evaporation

surface rocks

evaporation evapotranspiration

infiltration

groundwater

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6. What is water used for? Water is the most abundant substance in living things. Every day your body loses 1.5 to 2 litres of water through sweat, urine and respiration. You replace it by drinking water. Water is used in different ways, depending on the country. The main uses are: • Agriculture. To water crops. • Industry. Water is used in many industrial processes. • Domestic use. Drinking water is used for human consumption, cleaning, etc. Watering crops

How can you save water? Water is a scarce resource. You can reduce domestic water consumption if you ...: • Take a shower, not a bath. • Turn off taps when brushing teeth or soaping your body. • Load dishwashers and washing machines completely before use. • Install water-saving devices in the lavatory cistern.

7. What pollutes water? Water becomes polluted for many reasons. For example, as a result of:

Oil refineries consume a lot of water

• Waste water from industries and farmland. • Sewage water from towns and cities. • Oil slicks caused by the accidental spillage of crude oil at sea. • Agricultural fertilizers and pesticides which filter into the soil and pollute rivers and groundwater.

Some causes and prevention of water pollution Causes

Prevention

Rubbish thrown in the countryside, on beaches, in rivers, etc.

Pick up rubbish and place in rubbish bins.

Toxic waste from domestic use makes it difficult and expensive to purify water.

Do not throw paints, oils or solvents down the drain or toilet.

Chemical pollution

Recycle batteries. They release toxic chemicals into the soil, then into rivers.

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Cleaning water polluted by an oil slick

Activity 9. Use information from this page to make a water poster. Example: Take showers. Don’t throw rubbish on the beach. It pollutes the water.

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Hands on Studying the effects of temperature on condensation 60 °C

18 °C

6 °C

0 °C

Controlling variables in an experiment To see how temperature affects the condensation of water vapour, compare masses of air at different temperatures. Keep all other variables equal.

B

A

C

D

Keeping all the variables equal, and modifying only one is called controlling variables.

Procedure

1. Place four identical glasses on a table. Label them 4. Observe the table. What can you conclude from A, B, C and D. Place a thermometer in each one.

2. Put very hot water in glass A; water at room temperature in glass B; three ice cubes in glass C. Fill glass D with ice cubes. Make sure the four glasses are completely dry on the outside.

3. Wait twenty minutes. Then observe and note down the amount of condensation on the outside of each glass.

Water condensation outside the glass.

the effects of temperature on the process of condensation? Glass

Temperature

Appearance

A

60 ºC

No condensation

B

18 ºC

No condensation

C

6 ºC

Small drops

D

0 ºC

Large drops which slide down the glass

Controlling variables. The four glasses are surrounded by the same air, so we can assume that atmospheric pressure, particles in the atmosphere, humidity, etc., are the same for each glass. These are the controlled variables. Only the temperature varies. The temperature is the independent variable, that we changed for the purpose of the experiment. The amount of condensation of the humidity in the air depends on the temperature, so the condensation is the dependent variable.

Activity 10. Breathe on each glass to make the surrounding air more humid. Does the amount of condensation increase in each case? Which controlled variable have you now modified?

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Activities 11. This diagram shows the distribution of fresh water in the hydrosphere. Label the corresponding sections. A

C

17. Look at the diagram of the water cycle.

B

12. Water transports dissolved salts to the sea. Water also transports nutrients in our blood. What property enables water to do these things? 13. If you water the ground on a hot day, you notice the atmosphere becomes cooler.

a. Copy the diagram and label each process: evaporation, condensation, evapotranspiration, precipitation, surface runoff and infiltration. b. What role do plants play in the water cycle? 18. What are the main sources of water pollution caused by human activity? Example:

What causes this effect? How is it similar to feeling cold when you get out of a swimming pool or the ocean? 14. There is less difference between winter and summer temperatures on the coast, than in the interior of the country. What is the cause of this difference, and what property of water would explain it? 15. If you put a bottle of water in the lavatory cistern, this reduces water consumption. Why is this? 16. About 15 litres of water a minute flow through an open tap.

19. Fill a small bottle of water to the top. Close it tightly and put it in the freezer. Depending on the type of plastic, it may break or change shape. a. Why does this happen? b. Would this happen to a glass bottle? 20. Complete the chart. Water on Earth

Percentage of the total

Salt water rivers, lakes, Continental water

groundwater ice and snow surface fresh

a. A person cleans his teeth three times a day and takes a shower once a day. Calculate how much water he saves if he turns off the tap for two minutes while he cleans his teeth. b. And if he takes five minutes less in the shower?

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21. When water passes from the biosphere to the atmosphere, what is this process called? 22. Explain what role the Sun plays in the water cycle.

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THE HYDROSPHERE

What should you know? Water distribution

97 %: salt water. 3 %: fresh water, of which: • 68.7 %: is ice and snow from glaciers or at the Poles. • 30.1 %: is groundwater. • 0.3%: is surface fresh water. • The remaining 0.9%: is in the atmosphere and living creatures.

Properties of water

• • • • •

Movements of ocean waters

The water cycle

Uses of water

9

Good solvent. Transports substances inside living things. Absorbs large quantities of heat. Moderates temperature differences in climate. Anomalous dilation. Water dilates when it freezes. Cohesion: water molecules are attracted to other water molecules. Adhesion: water molecules can be attracted to other materials.

• Waves. Caused by the wind. Waves mix water, causing air-gas exchange. They cause erosion of cliffs, and transport materials. • Currents. Movement of large bodies of water by prevailing winds. Cause differences in water salinity and temperature. • Tides. Rise and fall of sea water levels due to gravitational attraction of the Moon and the Sun.

Water from the hydrosphere moves through the suface of the Earth and the atmosphere. The processes are: evaporation, evapotranspiration, condensation, precipitation, runoff and infiltration.

• For agriculture. To water crops. • For industry. Used in many industrial processes. • Drinking water has domestic uses. For human consumption, cleaning, etc. Water is contaminated by: • Waste water from industries and farmland. • Sewage waters from towns and cities. • Oil slicks at sea. • Fertilizers and pesticides filter into the soil and pollute rivers and groundwater.

Projects POSTER: Draw a frozen lake. Show the living things that exist under the ice. Add labels and text: These animals live... WEB TASK: Calculate the amount of water you use in one week for showers or baths.

Compare your consumption with your classmates’.

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UNIT

10 Minerals What do you remember? Look at the gold mine and gold sample in the photograph. • Where is gold is found? • Is gold a solid, liquid or gas? • Is it natural or man-made? • Do you think there is a lot of gold available on Earth?

Content objectives

Key language

In this unit, you will …

Comparing

• Learn the definition of a mineral

Diamonds are harder than talc.

• Identify the properties of minerals

Describing

• Classify minerals

Some minerals have a metallic colour. Mica can be scratched with a fingernail.

• Learn to use the Mohs Scale of Hardness

Classifying

• Use a mineral key to identify minerals

Non-silicates are classified into five groups.

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1. What are minerals?

Did you know that...?

Minerals are naturally occurring, inorganic, solid substances. They have a definite chemical composition and specific physical properties. All minerals must be: naturally ocurring ⫽

solid substances ⫽ not a liquid or a gas

not made by humans

The Earth’s crust is made up of rocks, and rocks are made up of minerals. Oxygen is the most abundant element in the Earth’s crust. More than half the weight of a rock is made up of oxygen!

definite chemical composition ⫽

inorganic ⫽ not from living things

calcite

the atoms composing the solid have an orderly, repeated pattern

All minerals are solid substances. Water and mercury have most of the characteristics of minerals, except they are liquid at room temperature. They are called mineraloids, not minerals. Pyrite. Like all minerals it is a naturally occurring, inorganic, solid substance. Pyrite has a definite chemical composition: iron sulfide.

Mercury. It is a naturally occurring, inorganic, liquid substance. Mercury is a mineraloid.

amber

Activities 1. Look at the photos. Answer these questions for each one: a. Is it a solid? b. Does it occur naturally, or does someone make it? c. Is it made from living things? d. Is it organic or inorganic? 2. Are they minerals or not? Answer using the table.

…

is is not

a mineral because

it is it is not

gold

diamond

natural. inorganic. solid.

Example: An animal bone is not a mineral because it is not inorganic.

water animal bone

plastic

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2. What are minerals composed of? Minerals are composed of one or more chemical elements. The chemical elements of each mineral are arranged in a particular way. A chemical element is a substance which is made up of only one kind of atom. An atom is the smallest particle of matter. Oxygen, hydrogen, iron and gold are examples of chemical elements.

smoky quartz

agate

milky quartz

The chemical composition and the main physical properties are the same for all quartz. Smoky quartz, agate and milky quartz are varieties of quartz. The colours are different because of impurities in the samples.

Does the chemical composition of a mineral change? Quartz is a mineral. The chemical composition of quartz is always the same, because it is always composed of the same elements. The chemical composition of a mineral determines its physical properties. Quartz from Spain has the same properties as quartz from America. Impurities in minerals Minerals can be found with impurities. Impurities are small amounts of other substances which are not part of the mineral. These impurities can change some of the properties of the mineral. For example, quartz is usually colourless, but it can be found in several different colours.

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Activities 3. Study the photos of quartz. What colours can you see? Why can quartz be several colours? 4. Research other varieties of quartz. What colours are they? a. b. c. d. e) f)

Amethyst Jasper Citrine Creolite Rose quartz Rock crystal

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3. How are minerals extracted and used? Mineral extraction and its consequences A

B

C

D

Minerals are found everywhere in the Earth’s crust. They are extracted in different ways. Some minerals are found dispersed in rocks. For example, 1kg of granite rock contains 340g of quartz. Other minerals occur in mineral beds in high concentration. They are extracted in: • surface mines when they are in layers which are relatively close to the surface. • underground mines when they are deep in the Earth’s crust. Extracting minerals can damage the environment in several ways. 1. Washing the soil to isolate minerals pollutes rivers and streams.

2. Surface mines destroy vegetation.

3. Lorries, and other heavy vehicles make a lot of noise. Traffic pollutes the air, soil and water.

4. Soil and rocks from excavation is left in huge tips.

Minerals are used in everyday life • At home: Fluorite is used in the composition of toothpaste. You might use talc after your shower. The salt you put on your food is the mineral halite. • At school: Your pencil is made of graphite. Your digital watch can be made using quartz, aluminium, gold or silver. • In the shops: Gold, silver and platinum are used to make jewellery. Precious stones are minerals: diamonds, sapphires and amethysts. Your dentist sometimes uses gold to fill teeth. • Construction materials: Plaster is made from talc. Cement is made from calcite. Glass is made from quartz.

Activities 5. Match each photo, A – D above, with its environmental impact, 1 – 4. 6. What minerals are used to make these things? –wedding rings – cement – glass – table salt 7. Research. a. Find out about other things which are made of minerals. b. What metals are obtained from minerals?

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4. How are minerals classified? There are many different minerals, found mainly in stones and rocks. Minerals are formed by the combination of chemical elements found in the Earth’s crust. Oxygen is the most abundant element of the Earth’s crust, about 47 %. Silicon is the second most common, about 28 %.

Silicates Oxygen and silicon combined together produce silicates. Silicates are the most abundant minerals on Earth.

The most abundant elements in the Earth’s crust Element

Percentage

Oxygen (O)

47 %

Silicon (Si)

28 %

Aluminium (Al)

7.9 %

Iron (Fe)

5.0 %

Calcium (Ca)

3.6 %

Rest

8.5 %

These common silicates make up many rocks: • Quartz. Usually found in granite rocks or sandy river sediments. Very hard. Used in jewellery. • Feldspar. Found in many rocks such as granite and basalt. Used in glass and ceramics industries. • Mica. Abundant in granite. There are two types: white mica, called muscovite and black mica, biotite. Used in electronic insulators and paints. • Olivine. Very common. Olive green in colour. Found in volcanic rocks. Used to make jewellery. Also used as an abrasive.

Activities 8. Use the information from the table of the most abundant elements to make a bar graph. 9. Summarise the information on silicates in a chart. Mineral Found in Colour Uses

Olivine. Olive green

Muscovite. White, yellow, grey. Glassy

Feldspar. White or pink. Glassy

Biotite. Black. Glassy

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Quartz. Several colours. Glassy

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Non-silicates Non-silicates are all the minerals that are not silicates. They are minerals that do not contain silicon. Common non-silicates are classified into groups as: • Native elements. These are minerals made up of a single element. For example, gold, silver, copper, and sulphur. • Oxides. This group of non-silicates are made up of oxygen and one other element. For example, oligiste is a source of iron ore from which iron is extracted.

Did you know that...? Diamonds and graphite are both made up of pure carbon. They have the same composition, but their internal organisation is different. Their properties are different, too. Diamond is the hardest mineral. Graphite is soft: it is used to make pencils.

• Sulphides. These are minerals made up of sulphur and a metal. Galena is the source of lead ore. • Carbonates. Minerals made up of carbon, oxygen and a metal. For example, calcite. • Halides. Minerals made up of a metal and chloride or fluoride. For example, halite.

Halite. White or transparent Calcite. All colours. Glassy. Stalactites form when calcite dissolves in water. The water evaporates and the calcite remains.

Activities 10. What is the difference between silicates and non-silicates? 11. List the minerals on these pages as silicate or non-silicate. 12. Match each term with its composition: a. oxide 1. metal ⫹ chloride / fluoride b. sulphide 2. oxygen ⫹ another element c. carbonate 3. sulphur ⫹ metal d. halide 4. carbon ⫹ oxygen ⫹ metal 13. Diamonds are 100 % carbon. Which group of minerals do they belong to? Native gold

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5. What are the properties of minerals? • Colour. Some minerals are always the same colour. For example, sulphur is always yellow. Quartz can be different colours.

• Streak. The streak of a mineral is the colour of the powder left on a streak plate (a piece of unglazed porcelain) when the mineral is scraped across it.

• Shape. Minerals can be geometric or irregular.

• Cleavage is how a mineral breaks up or cleaves. For example, mica cleaves in sheets, but galena cleaves in cubes.

• Lustre refers to the way minerals reflect light. Minerals can be classified as: – metallic: like metal: for example, pyrite – non metallic: waxy like oil or fat dull not shiny glassy like glass

• Hardness measures how a mineral reacts to being scratched. Mica cleaves in sheets.

Activities 14. Study the Mohs Scale of Hardness and describe each mineral. Talc is

harder than

apatite.

softer than

15. Describe your test for hardness. Oligiste leaves a red streak. a finger nail? Can a nail? you talc with a piece of glass? scratch a diamond?

What is the Mohs Scale of Hardness? In 1812, Frederick Moh devised the Mohs Scale of Hardness. He selected ten minerals and arranged them in order from 1 to 10. The mineral with the highest number is the hardest. The mineral with the lowest number is the softest. The Mohs Scale is used to compare the hardness of any mineral. Minerals not on the scale are given an intermediate number. For example, galena has a hardness of 2.5.

16. Look for information on minerals on the Internet. Classify more minerals by colour, lustre and hardness.

MOHS SCALE OF HARDNESS G

HARD: can be scratched with glass SOFT: can be scratched with a nail VERY SOFT: can be scratched F with a fingernail

G G

1 Talc

112

2 Gypsum

3 Calcite

F

4 Fluorite

5 Apatite

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Hands on Using a mineral identification key. Classifying minerals

1. Identify a mineral with this key: b. Study the colour: is it light or dark?

a. Study the lustre: is it metalic or non-metallic?

metallic

non-metallic

light

dark

c. Test the hardness. Use the Mohs Scale of Hardness and these tools. Each mineral can scratch only those minerals below it on the Mohs Scale. The harder the mineral, the harder the tool needed to scratch it.

fingernail

copper coin

steel nail

glass

2. Study the minerals in this unit, then copy and complete the chart. Mineral

Colour

Lustre

Hardness

Mica Olivine

dark green

Can be scratched with a nail

Calcite Pyrite Talc Quartz

FG

6 Orthoclase

F

VERY HARD: can scratch glass

7 Quartz

8 Topaz

9 Corundum

10 Diamond

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Activities

A

17. Look at photos A and B. a. Which one represents a mineral? b. Which one represents a mixture of different substances? A

26. Are these minerals? Explain why or why not. a. a rhinoceros horn b. a tortoise shell c. a snail shell

B B

C

18. Can you name minerals that do not contain oxygen? 19. Which of the following are characteristics of minerals? a. b. c. d. e. f. g.

They are inorganic. They are a combination of two substances. They have a definite chemical composition. They are artificial. They are natural. They are made of organic material. They are solids.

27. Copy and complete the table about the use of minerals. Give several examples for each place. MINERALS IN EVERYDAY LIFE Mineral halite At home

Use table salt

talc fluorite

At school In the shops

20. What do you call minerals with no silicon in their composition? How many main groups are there? 21. What number on the Mohs Scale of Hardness would these minerals have? a. A mineral that can be scratched by talc. b. A mineral that can scratch talc, and can be scratched by gypsum. 22. Study the minerals on pages 112 and 113 and test your partner: What mineral is this? Can you describe the colour? How hard is it? Is the lustre metallic or non-metallic?

Jewellery Construction

28. Many Ancient Egyptian statues are still standing today. The statue in the photo is made of alabaster. Describe alabaster: is it hard or soft? Explain your answer. Hint: alabaster is 2-3 on the Mohs Scale.

23. What minerals can you identify at home or at school? 24. Research. Where are diamonds obtained? What different colours of diamonds are there? Make a file card about diamonds. 25. Choose a mineral. Research its most important uses in daily life. Make a poster to illustrate these uses.

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29. Many people have mistaken pyrite for gold. This is why it is often called ‘Fools Gold’. Pyrite is quite easy to distinguish from gold. If you had a sample of each mineral, how would you distinguish them?

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What should you know?

10

MINERALS

Minerals are naturally ocurring, inorganic, solid substances with a specific chemical composition and specific physical properties. They are made up of elements. The most abundant elements in the Earth’s crust are oxygen (47 %) and silicon (28 %).

Mineral classification

There are two main groups of minerals. • Silicates are composed of silicon and oxygen. The most common silicates are quartz, feldspar, mica and olivine. • Non-silicates are classified by their chemical composition as: native elements, oxides, sulphides, carbonates and halides.

Properties

• Colour. Some minerals are always the same colour. Others, like quartz, can be different colours because they contain impurities. • Lustre refers to the way a mineral reflects light: metallic; non metallic. • Hardness measures how a mineral reacts to being scratched. Minerals are classified on a scale of 1 to 10. 1 is soft. 10 is the hardest. • Streak is the colour of the powder left when a mineral scratches a surface. • Cleavage is how a mineral breaks up: in sheets or cubes.

Extraction and uses

Minerals occur in high concentration in mineral deposits. They are extracted in surface mines or underground mines. Uses: • Sources of metal: lead, iron, etc. • Jewellery: gold, silver, diamonds and quartz • Construction materials: plaster, cement • Home: table salt, toothpaste, watches …

Projects EXPERIMENT AND REPORT: You cannot scratch quartz with a nail. Can quartz scratch the nail? PROJECT: Mineral Exhibit. Use the information from the table on page 113. Prepare a file card for each mineral. WEB TASK: What is your birthstone? What are some of its properties?

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UNIT

11 Rocks What do you remember? • What are rocks made up of? • Are all rocks solid, or can a rock exist in liquid state at normal temperature? • Can you name some things that granite and marble are used for?

Content objectives

Key language

In this unit, you will…

Expressing a purpose

• Explore some uses of rocks

Granite and marble are used for sculptures.

• Understand the relationship between minerals and rocks • Recognise common types of rock • Analyse how rocks are formed • Classify rocks by their properties • Discover the processes involved in the rock cycle

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Making impersonal statements Igneous rocks are formed from cooled magma. Rocks are divided into three main classes.

Describing a process Plutonic rocks form as magma cools slowly under the ground. Volcanic rocks form as lava cools rapidly on the surface.

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1. How are rocks used? In the past, stone was used to make buildings, bridges, city walls, aqueducts, roads, etc. Today, most modern constructions are not made of stone. However, they usually contain some form of rock.

– Ceramic materials are made of clay. They are used for tiles, bricks, and bathroom pieces like sinks and toilets. • Decoration. Granite and marble are the most popular. They are used for sculptures, floors, kitchen countertops, etc. They are easy to carve and polish to a smooth, shiny finish.

• Construction materials. Granite, limestone and slate are strong, decorative, and provide good insulation. They are used to make walls and roofs. They also serve as raw materials to manufacture other products.

• Containers. Clay is used to make pottery and china. After the pieces are decorated, they are glazed and fired. This makes them much stronger.

– Cement is made of limestone and clays. It is used to make concrete. Concrete is used for roads, bridges, dams and entire buildings. – Plaster is made of gypsum and other ingredients. It is used on interior walls.

A Stonehenge, in England, is made of sandstone.

E Many statues and monuments are made of marble.

• Fuels. Coal and oil are used in transportation, industry, heating and to produce electricity. • Chemical industry. Oil is used to make plastics, paints, fertilizers, synthetic fibres and many other products.

B The Roman aqueduct in Segovia is made of granite.

C Many buildings are decorated with stone.

F Clay is used to make plates and pottery.

D

G

Concrete, glass and metals are made from rock.

H

Refineries process oil into fuel. Plastics are made from oil.

Activities

Did you know that...?

1. Match each photo with one of the uses of rocks.

The Great Pyramid of Giza, in Egypt, was built mostly of limestone - more than 1,300,000 blocks!

2. Make a list of the uses of rocks. Use the text above. 3. Oil has more uses than most other rocks. Investigate “products made from oil” on the Internet. Make a list.

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2. What are rocks? The solid part of the Earth is made up of rocks. Rocks are any natural, inorganic material made up of minerals.

Some Monomineralic Rocks Mineral

Some rocks are made of a single substance. They are called monomineralic rocks. Others can be found in liquid form, for example, oil.

Rock

clay minerals

clay

halite

salt

calcite

calcite / limestone

quartz

quartzite

How are rocks classified? Rocks are divided into three main classes: igneous, sedimentary and metamorphic. • Igneous rocks are formed from cooled magma. Magma is molten rocky material below the Earth’s surface. • Sedimentary rocks are formed by the accumulation and compaction of sediment, for example, clay, sand or rock fragments. • Metamorphic rocks are formed from other rocks by the effects of heat and pressure. Forces inside the Earth cause a “parent rock” to change into another type of rock, without melting.

Did you know that...? Igneous rock is named after the Latin word “ignis” meaning “fire”.

Igneous rock. These rocks are formed by minerals joined together. In granite it is easy to see the various components.

Sedimentary rock. Conglomerate.

Metamorphic rock. Slate.

Activities 4. What are the three types of rock? Define them in your notebook. 5. What is the difference between minerals and rocks? Check your answer by looking at Unit 10.

mantle crust external core internal core

Composition of the Earth

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3. What are sedimentary rocks? Sedimentary rocks are classified into three groups: detrital, chemical and organic.

Did you know that...?

Detrital rocks are made up of fragments of other rocks that are stuck together.

Oil and coal are called fossil fuels.They are the most important energy resources for the planet.

Chemical sedimentary rocks are made of mineral crystals from oceans, lakes and groundwater that have dissolved in water. Organic sedimentary rocks are made of plant and animal remains which have been transformed into minerals.

Chemical

Formed by

6. Observe pieces of detrital rocks using a magnifying glass. Make drawings to show the differences. 7. Describe a rock from the table. Your partner guesses which one.

Properties

Conglomerate

Fragments of rock and some sand

Round or angular fragments

Sandstone

Small grains of sand

Grains break off if scratched

Clay

Very small grains

Different colours. Smells like wet earth when wet

Limestone (Many types)

Chemical reactions. All contain calcium carbonate.

Reacts to acids by producing bubbles

Gypsum Evaporation of the water in deposits Rock salt

Very soft. Can be scratched with a fingernail

Tastes salty

Coal

Remains of land vegetation

Soft, black. Burns easily

Oil

Remains of marine plants and animals

Thick, black liquid

Organic

Classification of Sedimentary Rocks

Detrital

Common sedimentary rocks

Activities

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4. How are sedimentary rocks formed? The formation of sedimentary rocks begins with the accumulation and consolidation of sediment or of rock fragments. Sedimentary rocks are made up of fragments of other rocks. The deposition of these sediments in layers, in lakes or seas, takes place over millions of years. The deposited sediments are transformed into compact, cohesive rocks. Rocks are fragmented by: Weathering. Rocks at the surface of the Earth are broken up by the action of atmospheric phenomena (changes in temperature, rain, acid rain), or by the activities of plants and animals. Erosion. These broken fragments of rocks are swept away by running water, glaciers, waves or wind. After heavy rains, the rivers transport mud, clay, sand and stones to the valleys.

Strata in sedimentary rock can be horizontal or folded. As the Earth's crust moves, the layers of rock get folded up.

The layers of sediment build up over millions of years to form different stratas of sedimentary rocks.

How are fossils formed? Sedimentary rocks sometimes contain remains of living things that lived millions of years ago. These remains are called fossils. Fossils become part of the rocks during the processes of compaction and cementation of sediments. Fossils provide invaluable information about the history of life on Earth.

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Tree trunks and leaf fossils can show the vegetation that coal comes from.

Ammonites are marine molluscs which lived during the Mesozoic period.

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Rock fragments join to form rock by two processes: Compaction. The weight of successive layers of sediment compacts the sediments more. This pressure reduces the spaces between the fragments and squeezes out the water. As a result, salt crystals are formed.

Activities 8. Where can you find examples of rock erosion in your country? Choose an example and say what natural phenomena caused the erosion. 9. How are fossils formed? Make a series of drawings to show the process.

Deposition of sediments

10. What two processes transform soft, wet sediment into sedimentary rock?

Compaction

Cementation. The rock fragments are stuck together with the salt crystal which formed when the water was eliminated. Each layer of sediments is transformed into a layer of sedimentary rock. This layer is called a stratum (plural: strata).

11. Summarise the information about coal and oil. Complete the chart. Coal & Oil

Similarities

Differences

Pressure

fragment mineral deposits

Cementation

How are organic sedimentary rocks formed? Two kinds of sedimentary rock are made up of organic material: coal and oil. Coal is made of terrestrial vegetation. Oil is made of marine plant and animal remains. • Coal. Millions of years ago, vegetation accumulated in swamps. Eventually, the vegetation was buried in the Earth’s crust, without air. Then, heat, pressure and bacteria changed it into coal. This type of rock is found in continental environments such as forests.

• Oil. Some sedimentary rocks contain oil. Millions of years ago, microscopic marine animals and plants (plankton) fell to the bottom of the sea. Sediment accumulated on top of this organic material. The material was buried underground without air. Eventually, heat, pressure and bacteria slowly changed the organic material into oil.

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5. How are igneous rocks formed?

Plutonic rocks: slow cooling, large crystals.

Igneous rocks are formed as a result of the cooling and solidification of magma. Magma is the melted, rocky material from below the Earth’s crust or mantle. Magma consists of silicates, water and gases at high temperature. Lava is magma on the Earth´s surface. There are two types of igneous rocks: • Plutonic (intrusive) rocks form as magma cools slowly under the ground over thousands of years. As a result, the mineral crystals are large. • Volcanic (extrusive) rocks form as lava cools rapidly on the surface of the Earth. As a result, the mineral crystals are tiny.

• Large, visible crystals Granite

• The most common rock in the continental crust • Many colours – pink to grey and black • Very hard and strong

• Heavy and hard Basalt Volcanic rocks: quick cooling, tiny crystals, vitreous. As a result, the crystals are not visible.

COMMON IGNEOUS ROCKS Formed by the solidification of magma

12. Look up plutonic in an encyclopedia or on the Internet. Where does the word come from? 13. Research: What is the difference between magma and lava? 14. In which type of rock can you see minerals most clearly? Why?

• Made up of quartz, feldspars and small quantities of mica and other minerals

• Dark or black colour • It may contain olivine crystals • It may have a few bubble holes • The most common rock on the ocean floors

• Mostly light colours Pumice

• Light weight and floats in water • Spongy texture from bubble holes

• Black and smooth Obsidian

• Looks like black glass • The edges can cut

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Activities

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6. How are metamorphic rocks formed? Metamorphism is a slow process which occurs deep in the Earth. The effects of temperature and pressure change the parent rock into metamorphic rock.

Activities 15. Do igneous or metamorphic rocks contain fossils? Why or why not?

Metamorphic rocks are formed deep within the Earth by the effects of intense heat and pressure on sedimentary, igneous or other metamorphic rocks.

16. Draw pictures of sedimentary, igneous and metamorphic rocks. Write the name on the back. Distribute the pictures. Say if your rock is sedimentary, igneous or metamorphic.

These rocks do not melt, but the minerals inside them are changed by heat and pressure. The rocks become hard and compact. Metamorphic rocks rarely have fossils. The formation of metamorphic rocks

sedimentary rock

Foliated Non-foliated

Classification of metamorphic rocks

Common metamorphic rocks

metamorphic rock

Appearance

igneous rock

magma

Properties

Slate

Usually black, slightly shiny because of the presence of mica

Hard, but can be separated into thin layers or sheets (foliation)

Marble

Many different colours. Often with veins

Does not separate into layers. Marble reacts with acids, such as vinegar or hydrochloric acid, producing CO2 bubbles

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7. What is the rock cycle? The rock cycle is a set of processes which form, change and recycle rocks over time. These processes can take thousands or even millions of years. The rock cycle is similar to the recycling process for glass. Used glass is transported from recycling bins to factories. There, it is crushed and melted to make new glass. Glass can be used and recycled many times. A similar recycling process occurs with rocks. On the Earth’s surface, weathering and erosion break down and transport rocks. Under the Earth’s surface, rocks go through processes which change them. As a result, they become new rocks. The cycle is continuous.

Rocky landscape, Cappadocia, Turkey

The rock cycle

F

F

and pre ss ur e

F

magma

F

me

Sedimentary rocks

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g lin coo

co mp ac

t ing

ing

F

F

F

el t

wea t

m

he r

F

hea t

re su es pr nd

g lt in

ing

Metamorphic rocks

F

sediments

ta

me

weat her ing

he a

g l t in

we

a th erin g

F

Igneous rocks

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Hands on Investigating weathering and sedimentation

1. Chemical weathering Chemical weathering occurs when rock components react chemically with a substance and are broken down. Prediction. Vinegar is an acid. What do you think will happen if you put it on the rock sample? Materials a piece of chalk or limestone a glass jar a balloon some vinegar Procedure

2. Physical weathering and sedimentation Physical weathering breaks down rocks into fragments. The deposition of these fragments in layers over millions of years results in compact, sedimentary rock. Prediction. Which rock fragments will be in the bottom layers and which the top layers? Materials a plastic bottle with a screw-on top 0.5 L water small and medium-sized stones sand

a. Put the rock into the jar.

Procedure

b. Add a few drops of vinegar.

a. Put the stones, sand and water in the bottle.

c. Stretch the balloon over the top of the jar.

b. Shake the bottle vigorously for one minute.

Observation

c. Wait for the solid matter to settle. Figure 2.

a. Wait and watch carefully. Figure 1.

Observation

b. Take notes to answer these questions. What happens to the rock? What happens to the balloon?

a. Observe the layers and draw a picture: – Which stones are on the bottom? And on the top? b. Why did the layers form this way?

Conclusions. What does this experiment tell you about weathering? Hint: What acids do you find in the air or water?

Conclusion. What does this experiment tell you about sedimentation?

Figure 1

Figure 2

Activities 17. Collect rock samples in your area. Which ones are sedimentary rocks?

18. Research on the Internet how limestone caves are formed. Is this process caused by physical or chemical weathering?

How can you tell?

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Activities 19. Copy and label the diagram to show the stages of erosion / weathering.

24. Clay and granite are rocks. Clay is soft and fragile. Granite is strong and hard. Can you explain why? 25. Study the photographs. Identify the rocks: marble or granite. Which is made up of only one mineral?

A

20. In volcanic eruptions, large amounts of gases escape into the atmosphere. Where do they come from? 21. Copy and label the stages of the rock cycle.

F

F

F

27. Are there any sedimentary rocks made up of granite, an igneous rock? Think and explain your answer. See the rock cycle diagram.

29. What is metamorphism? What two factors produce it? What do you call the rocks which result from this process?

F

F F

26. What type of rock can burn? Explain your answers.

28. Compare the origin of metamorphic rocks and the origin of igneous rocks.

F

F

B

F

30. How can a metamorphic rock become an igneous rock? 31. Can a sedimentary rock be transformed into another sedimentary rock?

F

32. If an igneous rock is under great pressure, what could happen? 22. Observe samples of sandstone and clay under a stereoscopic microscope or magnifying glass. a. What differences can you see? b. Can you see minerals in one or both rocks? c. Observe other rocks, such as conglomerate, granite or limestone. Draw pictures of them. d. Write a brief description of your pictures. 23. What is the difference between rock salt and sea salt?

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33. Imagine your school wants to buy a sign to place outside. You have information on two different signs: one made of limestone and one made of granite. Which one is better? Select the best sign, and write a report. Give reasons for your selection. 34. Blocks of stone are often used to build walls, and stone tiles are used for roofs. The most common rocks used for these purposes are slate and granite. Which one is used for walls? Which is used for roofs? Explain your answer.

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What should you know?

11

Rocks are formed by minerals. If the composition of the rock consists of only one mineral, the rock is called monomineralic. Rocks are classified into three types according to how they are formed: • Sedimentary rocks. Formed by the accumulation of compacted sediment. • Igneous rocks. Made of magma which has cooled. • Metamorphic rocks. Formed by high pressure and temperature. They are always in a solid state. The rock cycle is the combination of processes that rock and sediments undergo on the Earth’s surface and in its crust. Some of the main uses of rock are: construction materials, decoration, containers, fuels, the chemical industry.

Igneous rocks

Igneous rocks are made from magma: a mixture of melted rock and gases. There are two types.They can be: • Plutonic. Slowly solidified deep in the Earth. Crystallized minerals are apparent. For example, granite. • Volcanic. Solidified quickly on the exterior of the Earth’s crust. Homogeneous appearance, not crystalline. Basalt, pumice and obsidian.

ROCKS

Sedimentary rocks

Sedimentary rocks are usually found in layers, called strata. There are three types: • Detrital. Formed by the combination of fragments of different rocks and minerals. Conglomerate, sandstone and clay. • Chemical. Sedimentary rocks are made of mineral crystals from oceans, lakes and groundwater that have dissolved in water. Limestone, gypsum, salt. • Organic. These are formed by the accumulation of organic material. Coal and oil. These are known as fossil fuels.

Metamorphic rock

Metamorphism is the process of changes produced in solid rock by high temperatures and pressure. Metamorphic rock can be: • Foliated. These can be separated, cleaved, into layers. For example, slate, schist and gneiss. • Non-foliated. These can be broken into irregular shapes. For example marble, and quartzite.

Projects INVESTIGATE: Can some rock float? Drop a piece of pumice in water.

a. Does the pumice float or sink? b. Observe the pumice through a magnifying glass. What can you say about the structure? c. Is pumice sedimentary, metamorphic or igneous rock? How is it formed? What causes the holes? WEB TASK: How many active volcanoes are there on Earth?

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It’s elementary! Currently, more than 110 different chemical elements have been identified. Over 90 elements are found in nature. The rest are created only in laboratories as artificial elements. All these elements are classified in the Periodic Table of Elements according to their properties.

The first ten elements atomic symbol 1

H F

F

name of the element

F

F

atomic number

Hydrogen

Black - solid Blue - liquid Red - gas Purple - artificial

1

H

1

3

2

H

Be

Hydrogen 4

Li

Be

Lithium

Beryllium

Hydrogen is used as rocket fuel.

Li Hydrogen, hydrogen everywhere! About 90 % of the atoms in the Universe are hydrogen, about 9 % are helium, and all the other elements account for less than 1 %.

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Lithium is used for batteries.

Beryllium is used for structural components of space craft.

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B

C

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Boron is used in fireworks to provide a distinctive green colour, and in rockets for ignition.

He

Helium is mixed with oxygen and is used by deep sea divers.

Hard diamonds and soft graphite (found in pencil lead) are both forms of carbon.

Ne

Neon is used for advertising signs.

2

He Helium 5

N

6

7

8

9

10

B

C

N

O

F

Ne

Boron

Carbon

Nitrogen

Oxygen

Fluorine

Neon

Nitrogen in the soil is necessary for plant growth.

O

Plants and animals need oxygen for respiration. Oxygen is used for patients with respiratory problems.

F

Fluorine is present in toothpaste. It helps prevent dental cavities.

Activity 1. Turn to the Periodic Table, page 152. Choose another element and research its uses. As a class, make a poster of different elements and their uses in everyday life.

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UNIT

12 Matter and

its properties

What do you remember? • What is matter? • What unit of measurement is used to show the mass of matter? And to measure the volume? • What instrument do you use to measure the sides of a patio? What units would you use?

Content objectives

Key language

In this unit, you will …

Comparing

• Understand what matter is

Iron has more mass. It is denser than wood.

Measuring

• Learn how to measure the properties of matter

13.5 g per cubic centimetre. One milligram. Minus 459 degrees.

• Create a graph to show the relationship between two variables

Two scales are used to measure temperature. Time is measured in seconds.

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Making impersonal statements

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1. What is matter? Everything that takes up space and has mass is matter. Therefore, everything around us is matter. • General properties. These are the properties common to all matter: mass, volume, weight and density. • Specific properties. These are the characteristics that differentiate one kind of matter from another. They are colour, shape, size, texture, hardness, etc. They can be used to identify and describe matter.

Air is matter A

B

Balance two inflated balloons on a cane. (A) Then, burst one of the balloons. The balloons are no longer balanced. (B) This happens because the inflated balloon contains air, so it has greater mass than the burst balloon. Air has mass and occupies space, therefore it is matter.

The books you read and the pencils you write with are matter. The water you drink and the air you breathe are matter.

The International System of Measurements To measure matter, many types of units can be used. To compare measurements, however, everyone needs to use the same units. The most common system is the International System of Units. There are seven base units. All other units are a combination of these base units. • Base units are used to measure length, mass, time etc. These units are the metre, the kilogram and the second, etc. Some base units

Unit Symbol

Length

Mass

Time

Temperature

metre

kilogram

second

kelvin

m

kg

s

K

• Derived units are obtained from a combination of the base units. They are used to measure surface area, volume, speed and density, etc. These units are the square metre, cubic metre, metre per second, etc.

Did you know that...? In the past, people used their hands to measure an object, or steps to measure the length of a field.

Activities 1. What are the general properties of all matter? 2. You can’t see air. Explain why is it matter. 3. How long is this book? And how wide? Which unit of measurement would you use in the International System of Units?

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2. What is length? Multiples and submultiples of a metre

Length is the distance between two points. Length is a base unit. In the International System of Units, length is measured in metres.

Unit and symbol

Equivalent

millimetre (mm)

1,000 mm  1 mk

centimetre (cm)

100 cm  1 m

Did you know that...?

metre (m)

1m 1,000 m  1 km

kilometre (km)

This bar made of platinum and iridium was used as the International Prototype to define the metre as the international unit of length. It is displayed in the International Bureau of Weights and Measures, Paris.

Multiples and submultiples of a square metre

Surface area is the space occupied by the length and width of a body. It is a derived unit from length. In the International System of Units, surface is measured in square metres (m2).

Equivalent

square millimetre (mm2)

1,000,000 mm2  1m2

square centimetre (cm2)

10,000 cm2  1 m2

square metre (m2)

1m2

square kilometre (km2)

1,000,000 m2  1km2

F

3. What is surface area?

Unit name

How is surface area measured? To calculate the surface area of:

G

height

• Regular shaped objects. Use the mathematical equation corresponding to the shape.

G

F

base Surface area 

base length  height 2

• Irregular-shaped objects. Divide the irregular shape into regular ones, and calculate the area of each one. Then, add these areas together to calculate the total (estimation).

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• Circular objects. Use  multiplied by the square of the radius:  r2.

G

Radius

Surface area   r 2

F

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4. What is volume? Volume of the object

G

F

The volume of a solid is the amount of space it occupies. It is a derived unit from length. Volume is measured in cubic metres (m3). To measure the volume of: • Regular geometric solids. Use the corresponding mathematical formula. For example, to find the volume of a box, multiply the base (length x width) by the height.

• Liquids. Use a measuring cylinder to measure the volume.

Initial volume

• Gases. Fill a measuring cylinder with water. Place it upside down in a dish of water. Mark the water level in the cylinder: initial volume. Blow air through a tube into the cylinder. The air displaces some water. Mark the new water level: final volume. The difference between the two levels is the volume of gas added to the cylinder.

Final volume

Capacity is the amount of liquid a container can hold when it is full. For example, a bowl can hold more water than a cup. Capacity is measured in litres (L).

Volume of the gas

Measuring the volume of a gas

Capacity The volume of a liquid can be calculated by measuring the capacity of its container.

F

Measuring the volume of an irregular object

G

• Irregular-shaped solids. Use a measuring cylinder to measure the volume. Submerge the body in water, then measure the amount of water displaced.

Multiples and submultiples of a litre Unit and symbol

Equivalence in litres

Litre (L)

1L

Decilitre (dL)

0.1 L

Centilitre (cL)

0.01 L

Millilitre (mL)

0.001 L

Equivalences between volume and capacity Volume 1 m3

Capacity 1,000 L

3

1L

3

1 mL

1 dm 1 cm

3

1 mm

0.001 mL

Activities 4. What is the capacity of a container with a volume of 3.4 cm3? 5. How many 250 mL bottles do you need to fill a tank with a capacity of 10 L? Perfume is sold in small bottles because it is very expensive.

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5. What is mass? Mass is the amount of matter in a body. Mass is a base unit. Mass is measured in kilograms (kg). Scales are used to measure mass. Multiples and submultiples of a kilogram Unit and symbol

Equivalence in kilograms

ton (t)

1,000 kg

kilogram (kg)

1 kg 1kg  1,000 g

gram (g) decigram (dg)

1g

centigram (cg)

1g  100 cg

milligram (mg)

1 g  1,000 mg

10 dg

This prototype of the kilogram is in the International Bureau of Weights and Measures in Paris. The kilogram is a unit of mass.

A

B

C

Traditional scales compare mass with a standard weight. To do this, place the body to be weighed in a saucer (A). Add weights to the other saucer (B) until they are balanced (C).

Activities 6. A gold chain was weighed using the following weights: – one 100 g weight

– two 1 g weights

– one 500 mg weight

Can you calculate the mass of the chain in grams and milligrams? 7. A box of biscuits weighing 1 kg costs 3 €. A box weighing 250 g costs 1 €. Read and calculate: The 1 kg box of biscuits is times bigger than the 250 g box. How much money do you save if you buy the big box?

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This electronic scale can measure mass to one hundredth of a gram.

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6. What is density? Density is the relationship between the mass and the volume of a body, that is, how concentrated the mass is in a specific volume. Density is measured in kg/m3 or g/cm3. Iron has a higher density than wood. These two blocks, one of iron, and one of wood, have the same volume. The block of iron has more mass, or amount of matter, so it is harder to move. The block of iron feels heavy for its size. The mass of one litre of oil is 900 g.

easy to move →

hard to move → → →

The relationship between mass and volume: • The greater the mass is, the greater the density. • The greater the volume is, the smaller the density. Density is a specific property of matter. It helps differentiate one substance from another. Density 

mass

The mass of one litre of water is 1,000 g.

Did you know that...?

volume

Generally speaking, solids have a higher density than liquids. Liquids have a higher density than gases. For example, air weighs very little because it has little mass: it feels light for its size.

Activities

Oil floats on water because it is less dense. For the same volume of oil and water, water has more matter than oil. This is the property of density.

8. Which of the substances in the table on the right float on water? Why do the others sink? Densities of some substances 9. These two bodies have the same mass: the crosses represent particles of mass. Which of them has the highest density? Explain. x x

x

x

x

x

A

x

10. These two bodies have the same volume, but different mass. Which body has the highest density? x

x

x

x

B

C

x

x x

D

Substance

Density (g/cm3)

Water

1.0

Oil

0.9

Petrol

0.7

Lead

11.3

Iron

7.9

Mercury

13.5

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7. What are temperature and time? What is temperature? Temperature is used to measure the thermal state of a body. This measurement is related to the body’s internal state. Temperature is related to the amount of heat a body gives off or absorbs. A hot body will heat a cold one until they are both the same temperature. Thermometers are used to measure the temperature of bodies. In the International System of Units, the kelvin (K) is the unit for temperature. Another unit, degrees Celsius (°C) is used frequently. Some countries, (especially the United States of America) use another measurement, Fahrenheit (ºF). Here are some equivalents: Temperature scales

kelvin

Celsius

Fahrenheit

Unit (symbol)

kelvin (K)

degree Celsius (°C)

degree Fahrenheit (°F)

Boiling point of water

373.15

100

212

Melting point of ice

273.15

0

32

Absolute zero

0.

Temperature does not depend on the amount of matter. For example, imagine that the temperature of the water in a glass is 60 ºC. If you pour half of the water into one glass and half in another, the temperature in each one will still be 60 ºC. What is time?

273.15

Penguins are much warmer than the place they live in. Their feathers stop them losing heat.

459.67

Did you know that...? The following units are also used to measure time: 60 seconds = 1 minute (min) 1 hour (h) = 60 minutes 1 day (d) = 24 hours 7 days = 1 week 365 days = 1 year (366 days in a leap year) 100 years = 1 century

Everyone is aware of the passing of time. Even without a watch, it is easy to tell when this class is going to end. The position of the Moon or the Sun indicates if it will soon be daytime or nighttime.

Activities

Time is used to measure the passing of events. In the International System of Units, time is measured in seconds (s).

11. Convert these temperatures into degrees Celsius. (ºC +273 = K) a. 285 K b. 290 K c. 254 K 12. How many things can you list related to measuring time? Don’t forget “school timetable”.

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Hands on Analysing results. Using graphs. A graph can be used to analyse the data from an experiment. A graph also shows the relationship between two variables. thermometer

water

Graphs show how one base quantity varies in comparison with another. For example, the temperature of a mass of water will increase when it is heated.

To see how the temperature increases, heat a glass with 500 mL of water. Measure the temperature every 2 minutes.

Time (min)

Temperature (°C)

00

018

01

018

03

032

05

046

07

060

09

074

11

088

13

100

15

100

Follow these steps to draw the graph: 100

– Write the time scale on the horizontal axis (min). – Write the temperature scale on the vertical axis (ºC).

2. Mark the points on the graph. Mark points on the graph where the time values intersect with the temperature values.

3. Draw a line to join all the points. Use a ruler to make the line straight.

Temperature (°C)

1. Draw the coordinate axes on squared paper.

80

60

40

20

0 0

1

3

5

7

9

11

13

15

Time (min)

Activities 13. Describe the graph. Why do you think the line begins and ends horizontally? 14. Do the same experiment with 300 mL of water. a. Stir the water so the temperature is the same in all parts of the glass. b. Measure the temperature of the water every two minutes. c. Make a table and draw a graph. d. Compare the two graphs. Are there any differences? e. Does the amount of water affect the time it takes to heat up?

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Activities 24. Look at the picture. Which of the two substances is denser? Why?

15. Measure the surface of a piece of paper and give the result using the correct units of measurement. 16. Which multiples and submultiples of the metre would you use to calculate the following measurements? a. b. c. d.

The distance between two towns. The diameter of the head of a nail. The length of your pen. The length of the classroom.

B A

17. Research on the Internet different types of calendar. Which calendar do you use in your country? 18. Copy and complete the following table using the formula to calculate density. Substance

Mass (kg)

Volume (m2)

Cedar wood

57,000

100

Water Lead

Aluminum 96º alcohol

570

1 22,600

Gold Mercury

Density (kg/m3) 1,000

2 3

54,400

4

5,400

2

25. A 3 L container of olive oil has a mass of 2.7 kg. Calculate the density of olive oil. 26. Oil spills occur when the cargo from an oil tanker pours into the ocean due to an accident, for example, Prestige, in 2002. Taking into account that the density of oil is less than that of sea water, will the oil float or sink? What consequences do oil spills have on the environment?

19,300

27. What base quantities are also general properties of matter?

1

800

19. Give the following measurements in centimetres. a. 320 mm b. 3.5 m c. 2 km 20. If you mix water with oil, it separates into two layers. Which liquid floats on top?

28. Research the history of the different ways to measure temperature. Where do the names Fahrenheit, Celsius and Kelvin come from? 29. Copy and complete the table: Length Mass Time

3

Remember: the density of water is 1 g/cm , and the density of oil is 0.9 g/cm3.

Temper- Surface Volume ature area

Unit Symbol

21. The density of iron is 7.9 g/cm3. If a nail made of iron has a mass of 20 g, what is its volume? 22. Measure the surface area of a piece of paper. Give your answer using the International System of Units. 23. A school wants to build a new sports field. It needs to include: – a football pitch measuring 100 m x 100 m – a basketball court measuring 18 m x 15 m – a tennis court measuring 23.77 m x 8.23 m How many square metres are needed for the sports field?

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ºC

K

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MATTER

What should you know? Properties

Matter is anything that has mass and volume. The properties of matter are: • General properties, common to all matter: – Mass – Volume • Specific properties: those which differentiate one substance from another.

Base quantities

Base quantities are all independent. They are measured in base units. • Length is the distance between two points. The unit for length in the International System of Units is the metre (m). • Mass is the amount of matter in a body. The unit for mass in the International System of Units is the kilogram (kg). • Temperature is the thermal state of a body. The unit for temperature in the International System of Units is the kelvin (K). • Time measures the passing of events. The unit for time in the International System of Units is the second (s).

Derived quantities

Mathematical combinations of base units are called derived units. • Surface area is the extension of a body in two dimensions. The unit for surface area in the International System of Units is the square metre (m2). • Volume is the space occupied by a body. The unit for volume is the cubic metre (m3). • Density is the relationship between the mass and the volume of a body. The unit for density is the kilogram per cubic metre (kg/m3).

12

Projects EXPERIMENT: Think up an experiment to prove the hypothesis: A digital watch measures

time more accurately than an hour glass. Describe: a. The equipment you used.

b. Procedures.

c. Conclusions.

WEB TASK: How warm is 50 degrees Fahrenheit? How big is a 30 inch TV screen?

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UNIT

13 Everything is matter What do you remember? • What are icebergs and glaciers made of? • What state of matter is ice? • Can water exist in more than one state? • Is sea water made up of one substance or several? • What is fresh water made of?

Content objectives

Key language

In this unit you will …

Describing a process

• Differentiate changes of state of matter

When a liquid is heated, it boils. When a solid is heated, the particles gain energy.

• Recognise the conditions in which changes occur

Making generalisations

• Differentiate pure substances and mixtures

Most common substances are mixtures. Most plastics are made from petroleum.

• Evaluate the need for recycling waste

Describing

• Draw conclusions from examining the components of a mixture

A pure substance has only one component. A compound contains two or more elements.

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1. Which are the states of matter? Matter can exist in three physical states: solid, liquid and gas. Matter normally exists in one state in nature. However, water can exist naturally in all three states: ice, water and water vapour.

Solids have a fixed shape if no pressure is exerted.

Shape Volume

Liquids have no fixed shape. They adapt to a container.

Gases have no fixed shape. They occupy all available space.

Solids

Liquids

Gases

Hold shape

Shape of container

Shape of container

* except for water

– Fixed volume – Fixed volume – Solids expand – Liquids expand if heated, or contract if cooled* if heated or contract if cooled.

– Volume of container – Gases expand to occupy all available space.

Fluidity

– Solids cannot flow.

– Can flow. They spread if not in a container.

– Can flow. They spread if not in a container.

Density

– Usually have a high density: many particles in a small volume

– Quite high density: a lot of particles in a small volume

– Low density: few particles in a large volume

Compressibility

– Difficult to compress

– Quite difficult to compress

– Easy to compress

The states of matter according to particle theory

Activities

•

1. In which of the states of matter are the particles closest together? Why is it very difficult to compress solids and liquids?

Matter is made up of tiny particles. Between them are empty spaces.

• The particles within matter are in constant motion.

2. Describe how the particles move in solids, liquids and gases.

• Temperature affects the speed of particles.

3. Why do solids generally have a higher density than liquids, and liquids a higher density than gases?

• There are forces which attract the particles.

Solids The particles are very close together, held by strong forces of attraction. They vibrate but do not change position.

Liquids The particles are close together, held by weak forces of attraction. They have some freedom of movement. They can flow and slide easily.

Gases The particles are far apart and move quickly in all directions. The particles have no force of attraction. They collide with each other.

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fusion

vaporisation

solidification

condensation

2. How can matter change its state?

Solid to liquid • When a solid is heated, the particles gain more energy and move more. The forces of attraction between the particles are weakened. • At a certain temperature, the particles have enough energy to break free from their positions. When a solid changes into a liquid, the process is called melting or fusion. • The reverse process, when a liquid is cooled and changes to a solid, is called solidification. • The temperature of a substance at fusion and solidification is always the same one. Liquid to gas

Did you know that...? Above its boiling point a substance is a gas. Between its melting point and boiling point a substance is a liquid. Below its melting point a substance is a solid.

Activities 4. Study the diagram. Which arrows (red or blue) indicate changes of state produced by heating? Which arrows correspond to changes produced by cooling? liquid

• When a liquid is heated to a certain temperature, it boils. The particles have enough energy to break free from their positions. When a liquid evaporates into a gas, the process is called vaporisation. • The reverse process, when a gas changes into a liquid, is called condensation. Solid to gas • When a solid changes into a gas without first becoming a liquid, the process is called sublimation. For example, naphthalene balls change slowly into a gas. • When a gas changes directly into a solid, the process is called regressive sublimation. For example, snowflakes change from water vapour into solid snow.

142

solid

fu sio n so lid ifi ca tio n

Particles of matter do not change from one state to another. They only change their arrangement or their energy. When matter changes state, no mass is lost.

va po ris at co io nd n en sa gas tio n

sublimation regressive sublimation

5. 50 g of iron is melted. How much liquid iron is produced? Why is this?

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3. What are mixtures? Most common substances are mixtures. For example, the air in the atmosphere is a mixture of various gases. Mixtures that appear uniform are called homogeneous. Mixtures where more than one part is distinguishable are called heterogeneous. Heterogeneous mixtures In some mixtures, the components are clearly distinguishable. For example, most rocks contain a mixture of different minerals.

Granite is a heterogeneous mixture. It is composed of minerals that are clearly distinguishable (each colour is a different mineral).

Steel is a homogeneous mixture. It is made from iron and carbon.

Homogeneous mixtures In homogeneous mixtures, you cannot distinguish each component with the naked eye. They have a uniform composition. For example, sea water, air, and vinegar.

Activities

What is a solution?

6. Copy and complete the chart. Add more examples.

A solution is any homogeneous mixture. Solutions are usually liquid mixtures, that is, liquids with solid substances, such as water with sugar. The sugar is dissolved evenly throughout the liquid. The simplest solutions consist of two components: a solvent and a solute.

Mixture air

Components

Homogeneous / Heterogeneous

nitrogen, oxygen, argon homogeneous

steel

iron and carbon

granite

various minerals

However, solutions can be solid, liquid or gaseous: – Solids within solids: alloys are special solutions: all their components are solids. For example, steel (iron mixed with carbon). – Liquid within liquid: alcohol dissolved in water. – Solid within liquid: salt dissolved in water. – Gas within liquid: CO2 dissolved in fizzy drinks. – Gas within gas: air (nitrogen, oxygen, argon, etc.)

Solvent. The liquid part (often water)

7. Look in your kitchen for mixtures and label them homogeneous or heterogeneous: mayonnaise, tomato sauce, paper, pineapple juice, honey, a drink of coffee, coke, chicken soup, fruit yogurt.

Solute. The dissolved substance Solution

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4. What are pure substances? hydrogen

oxygen

A pure substance has only one component. It has a homogeneous look. It has unique properties that characterise it, for example, its density. These properties distinguish it from every other substance. Pure substances in nature can be either chemical compounds or elements. • Chemical compounds. A chemical compound consists of two or more elements joined up. The atoms are from different elements. Compounds have a fixed composition: water is always made up of two atoms of hydrogen and one atom of oxygen. It can be expressed as H2O. water Water is a compound. It is made up of two parts hydrogen to one part oxygen. Twice as much hydrogen as oxygen is obtained when water is broken down.

• Chemical elements. A chemical element cannot be broken down into simpler substances. About ninety chemical elements can be found in nature. Hydrogen and oxygen are chemical elements.

5. What are physical and chemical changes? A physical change does not change the composition of the substance. In a chemical change, where there is a chemical reaction, the substance is changed to a new kind of substance.

Activities 8.

9.

Physical change. If you cut paper into tiny pieces, each piece is still paper. When water changes into ice or vapour, it is still water.

144

Chemical change. When rust appears on a piece of iron, a new substance has been formed: iron oxide. When paper is burned, you can no longer see the pieces of paper. A new substance has been formed: ash.

What are the differences between pure substances and homogeneous mixtures. How are they similar? Classify these things: homogeneous or heterogeneous mixtures, or pure substances: a. sand and water b. oxygen c. iron d. water e. milk and chocolate powder

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Hands on Checking a hypothesis. Separating mixtures Using the filtration method The filtration method is good for separating an insoluble solid from a liquid. (An insoluble substance does not dissolve in water.) You are going to separate a mixture of water and sand using this method. The liquid passes through the filter, but the solid particles cannot go through. Materials – water – a beaker – a funnel – some filter paper – a container for the mixture of water and sand

1. Put the funnel into the beaker. Place the filter paper in the funnel.

2. Pour the mixture into the filter paper. 3. Remove the sand that has stayed behind in the filter paper.

Using the decanting method The decanting method is useful for separating a heterogeneous mixture of two liquids that have a different density. You are going to separate a mixture of water and oil using this method. Materials – water – oil – spoon – a container for the mixture of water and oil

1. Leave the mixture to rest until the particles of the liquid with the least density (oil) settle on top of the particles with the highest density (water).

2. Use a spoon to separate the liquid that is at the top of the beaker.

Activities 10. Does sand dissolve in water? Is a mixture of sand and water homogeneous or heterogeneous?

11. Copy and complete the text. Sand dissolve in water. When you mix sand and water you get a mixture. Sugar in water to form a solution. A solution is a mixture.

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6. What are synthetic materials? Synthetic materials do not exist in nature. They are obtained from natural substances which are transformed by chemical processes.

Activities

Fibre optic is a fibre made of glass or plastic. It is a long, fine tube which light travels along.

12. What materials would you use to make the following products? a. a boat b. a modern office building c. parts of an aeroplane d. a strong container to hold water e. a cable for telephones Say why in each case.

Carbon fibre is made up of mainly carbon atoms. It is an extremely thin fibre. Each fibre is incredibly strong. The fibres are woven together to create a very resistant material.

13. What properties of carbon fibre make it ideal for making a bicycle?

Synthetic materials are used to manufacture many products in modern, industrialised societies because of their special properties. Some of the most popular synthetic materials are: Plastic. Most plastics are made from petroleum. There are many different kinds, used to make a multitude of things. Glass is made from silica. Fibreglass is made from extremely fine fibres of glass, woven together.

Some properties of synthetic materials Material Properties

Plastic

Glass

– impermeable

– fragile, but hard

– light, flexible – resistant

Fibreglass

Fibre optics – excellent conductor of light

– light

– does not rust

– flexible and strong

– lets light through

– does not rust

– does not rust

– elastic

– does not rust Used for

multiple uses

Carbon fibre is strong but elastic. It has many uses in aviation

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Carbon fibre

– resistant – does not rust

multiple uses

boats, car bodies

Equipment for water sports is often made of fibre glass

cables for telephones, computers

cars, bikes, tennis rackets, aeroplanes

Fibre optics can conduct vast quantities of light or information at very high speed

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7. Why is recycling important? Solid waste: example

Every year, modern societies generate more and more rubbish. Urban solid waste is unwanted solid and semi-solid materials from homes, commerce and industry.

organic matter 30 %

paper 25 %

textiles 10 %

This waste can be harmful to the environment. Some of it is toxic. It needs to be treated or recycled. What can you do to help? You can reduce solid waste in the home, and recycle some of it. Recycled materials can be transformed into new raw materials.

plastics 7 %

glass 10 % metals 8 %

other 10 %

DO

Activities

Reuse materials: plastic bags, writing paper.

14. Copy and complete the table about waste in your home.

Recycle paper, glass, tins and plastic.

Organic

Take old medicines, paints and batteries to

vegetables leaves

collection dumps. Use rechargable batteries. DON’T Buy things with a lot of unnecessary packaging. Dump rubbish on the beach or in the countryside.

Toxic medicines paints

Recyclable bottles newspapers

15. Make a Do / Don’t poster about how to help reduce solid urban waste. 16. Investigate how urban solid waste is removed in your own area.

What happens to recycled waste? transport waste collection gl as s

domestic consumption co m po st

pl as tic

m et al

waste collection

rubbish dump

raw materials

processing and manufacturing

pa pe r

ss ce ro p g lin yc c re

toxic waste

incineration

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Activities 17. Read and classify: solid, liquid or gas. a. oxygen b. water c. granite

d. hydrogen e. oil f. steam

g. salt h. iron

B

-cornflakes and milk -butter and salt

-water and oil -water and ink

23. Can mixtures be compounds? Why or why not?

18. Identify: element, compound, mixture. A

22. Could you make a solution of the following substances? Say why or why not in each case.

Hint: A chemical compound consists of two or more elements joined up.

C

24. Copy and complete the following phrases.

19. Copy and complete the table with the properties of the three different states. Shape

Volume

Flows / does not flow

Solids

a. b. c. d.

The change from solid to liquid is called… The change from gas to liquid is called… The change from liquid to gas is called… The change from liquid to solid is called…

25. Indicate the solvent, the solute and the solution in this drawing. C

A

Liquids

B Gases

20. Give reasons for your classification in activity 17. 1. It flows easily. 2. It is easy to compress. 3. It cannot be compressed. 4. It has no fixed shape. 5. It has a fixed shape. 6. It has a fixed volume and shape. 7. It takes the shape of its container. 8. It can spread out into a space. Example: a-4. Oxygen is a gas: it has no fixed shape. 21. Classify the changes: physical or chemical. Give a reason. a. Paper is burned and changes into ashes. b. A rusty piece of metal. c. Clothes drying in the Sun. d. Lava cools down and solidifies. e. Water is broken down into hydrogen and oxygen.

It’s a

148

chemical physical

change because the substance

is the same. changes.

26. All substances can be found in any one of the three states of matter, if the conditions are right. a. Is it is possible to find iron in a liquid state on Earth? b. Is it possible to find water in a gaseous state? 27. Draw how you think particles of air are organised inside a container. Represent the air particles with dots. Then, draw the particles again after half the air has been removed. 28. Cartons are made with several layers of cardboard and polyethylene. The polyethylene is in contact with the liquid. It is a light plastic that does not let in air, humidity or bacteria. Cardboard makes the container harder. a. Why is polyethylene a good material to store food? b. What would happen if the container were made only of cardboard? 29. If you wash up a glass and leave it to dry, what has happened to the water on the glass? Would it dry faster in a cold room or a warm one? Why? What is the name of this process?

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What should you know? Matter can exist in three different physical states: • Solid: Fixed shape and volume. High density. • Liquid: No fixed shape. Fixed volume. It can flow. Quite high density. • Gas: No fixed shape. No fixed volume. It can flow and be compressed. Low density. A substance can change from one state into another. F

Physical states

13

Liquid G

fu si so on lid ifi ca tio n

n io at ris n po tio va sa en nd co

G

sublimation

EVERYTHING IS MATTER

G

F

Solid

F

Gas

regressive sublimation

Particle theory

• Matter is made up of tiny particles, surrounded by empty spaces. • The particles within matter are in constant motion. • There are forces which attract the particles. Particle theory describes changes from one state into another.

Mixtures

Matter can be classified by its appearance as: • Heterogeneous: the appearance is not uniform. The components can be distinguished. • Homogeneous: appearance is uniform. The components cannot be distinguished. Most common substances are mixtures. Solutions are homogeneous mixtures of two or more substances, made up of: • a solvent: the most abundant component. • a solute: the least abundant part of a solution.

Pure substances

There are two types: • Chemical compounds: Can be broken down chemically into simpler substances. • Elements: Cannot be broken down into simpler substances

Projects INVESTIGATE: Research other methods for separating mixtures. Display the results in a poster. Use diagrams and explanations. WEB TASK: What is the fourth state of matter? Investigate.

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UNIT

14 Atoms and elements What do you remember? • What is all matter composed of? • What gases are there in the air? • Which gas predominates? • Which gas do living things breathe?

Content objectives

Key language

In this unit, you will …

Describing

• Learn about the basic components of matter

Magnesium is a silvery white metal. Silicon is a solid, non-metal substance.

• Identify elements in the PeriodicTable

Indicating location

• Differentiate atoms, elements, molecules and crystals

Magnesium is found in minerals. Carbon is found on the Earth´s crust.

• Interpret some chemical formulas

Comparing

• Prepare a scientific report

Hydrogen is the most abundant gas in the Universe. Oxygen is the most abundant element on Earth.

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1. What is matter made of?

electrons protons

All matter is made up of atoms. An atom is the smallest particle of matter which can exist alone. It has all the properties of matter to which it belongs. Atoms are so small, they cannot be seen under a microscope. For example, one gram of copper contains more than nine thousand trillion atoms. The structure of an atom At the centre of an atom is a core called a nucleus. The nucleus is made up of particles called protons and neutrons.

nucleus neutrons

Protons have a positive charge (⫹). Neutrons have no charge. This means that the nucleus has a positive charge. Extremely small particles called electrons orbit the nucleus. Electrons have a negative charge (⫺). They are attracted to the positively charged protons in the nucleus.

The structure of an atom

Carbon atom

Nitrogen atom

Between the nucleus and the electrons there is nothing, so most of an atom is empty. The atomic number The atomic number of an atom is the number of protons in the nucleus. Each atom has a unique atomic number.

6 protons

7 protons

Carbon atoms and nitrogen atoms have different

2. What are elements?

atomic numbers: 6 and 7, respectively. As a result, they are different elements with very different properties.

An element is a substance that contains one type of atom. It cannot be broken down into anything simpler by chemical reaction. The atoms of one element are different to the atoms of every other element. For example, oxygen is made up only of oxygen atoms. Hydrogen is made up only of hydrogen atoms. Consequently, an atom is the smallest part of an element.

Did you know that...? All matter is made up of the atoms of one or more elements. There are about 90 different elements found in nature.

Activities 1. In what ways are some atoms different from others? 2. Why is most of the structure of an atom empty? 3. Draw a carbon atom and label nucleus, protons, neutrons and electrons.

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3. How are elements classified? All the elements found on Earth are classified in the Periodic Table of Elements. Each element is represented by a symbol consisting of one or two letters.

Black - solid Blue - liquid Red - gas Purple - artificial

For example, the symbol for hydrogen is H and for magnesium it is Mg. atomic number

1

2

3

4

5

6

7

8

9

10

11

Mg

name of the element

The Periodic Table of Elements 12

13

12

F

Magnesium

F

14

F

In the Periodic Table, the elements are grouped according to their atomic number. Elements with similar chemical properties are in the same column.

15

16

atomic symbol

17

1

2

H

He

Hydrogen

Helium

1

3

4

8

9

10

C

N

O

F

Ne

Lithium

Beryllium

Boron

Carbon

Nitrogen

Oxygen

Fluorine

Neon

12

13

14

15

16

17

18

Na

Mg

Al

Si

P

S

Cl

Ar

Sodium

Magnesium

Aluminium

Silicon

Phosphorus

Sulphur

Chlorine

Argon

20

21

22

23

K

Ca

Sc

Ti

Potassium

Calcium

Scandium

Titanium

4

37

38

39

40

24

41

42

Y

Zr

Nb

Rubidium

Strontium

Yttrium

Zirconium

Niobium

57

72

Cr

V

Sr 56

25

26

Mn

Vanadium Chromium Manganese

Rb 55

73

43

Mo

Tc

27

75

29

30

31

32

33

34

35

36

Fe

Co

Ni

Cu

Zn

Ga

Ge

As

Se

Br

Kr

Iron

Cobalt

Nickel

Copper

Zinc

Gallium

Germanium

Arsenic

Selenium

Bromine

Krypton

44

Ru

Molybdenum Technetium Ruthenium 74

28

76

45

46

47

48

49

50

51

52

53

54

Rh

Pd

Ag

Cd

In

Sn

Sb

Te

I

Xe

Rhodium

Palladium

Silver

Cadmium

Indium

Tin

Antimony

Tellurium

Iodine

Xenon

77

78

79

80

81

82

83

84

85

86

Cs

Ba

La

Hf

Ta

W

Re

Os

Ir

Pt

Au

Hg

Tl

Pb

Bi

Po

At

Rn

Cesium

Barium

Lanthanum

Hafnium

Tantalum

Tungsten

Rhenium

Osmium

Iridium

Platinum

Gold

Mercury

Thallium

Lead

Bismuth

Polonium

Astatine

Radon

87

7

7

B

19

6

6

Be

11

5

5

Li

2

3

18

88

89

104

105

106

Fr

Ra

Ac

Francium

Radium

Actinium Rutherfordium Dubnium Seaborgium

Rf

58

LANTHANIDE SERIES

F

ACTINIDE SERIES

F

6

59

Ce Cerium 90

7

Db

Sg

60

Pr

107

Hs

Bohrium

Hassium

61

Nd

108

Bh

62

Pm Sm

Praseodymium Neodymium Promethium Samarium 91

92

93

Th

Pa

U

Thorium

Protactinium

Uranium

Np

94

Pu

109

Mt

110

Ds

111

Rg

Meitnerium Darmstadtium Roentgenium

63

Eu

64

Gd

Europium Gadolinium 95

96

Am Cm

Neptunium Plutonium Americium

Curium

65

Tb Terbium 97

Bk

66

67

Dy

68

Ho

Dysprosium Holmium 98

99

Cf

69

Yb

Lu

Erbium

Thulium

Ytterbium

Lutetium

Fm

101

Md

102

No

4. Find platinum, gold and mercury in the periodic table. How many protons does each element have? 5. Can you find any other metals in the Periodic Table? 7. Say the letters of a symbol. Your partner says the element.

152

103

Lr

Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium

Activities

6. How are elements grouped in this Periodic Table?

71

Tm

100

Es

70

Er

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4. How are atoms organised? The noble gases are monoatomic. In others words, they exist as single atoms: they do not join up with each other to form molecules. The noble gases are helium, neon, argon, krypton, xenon and radon. Atoms are organised in different ways.

Did you know that...? Helium, a noble gas, is lighter than air. It is used to fill party balloons.

The atoms of most elements join up with each other to form molecules. Molecules are made up of two or more atoms. There are two types of molecules: • Simple molecules consist of two or more atoms of the same element joined together. • Compound molecules consist of a combination of different atoms joined together.

Compound molecule Water (H2O)

Simple molecule Oxygen (O2)

Crystals consist of atoms or molecules arranged in a regular, organised structure. Each crystal has a different shape and unique properties. There are two types of crystals: • Simple crystals consist of groups of atoms of the same element joined together in an organised structure. For example, metals. • Compound crystals consist of groups of atoms from different elements joined together. For example, common salt is sodium chloride.

O2 is an oxygen molecule made up of two oxygen atoms.

A water molecule is H2O: two hydrogen atoms joined with one oxygen atom.

Every chemical element has its own specific properties. The combination of elements produces millions of compound substances with very different properties.

Activities 8. Look at the periodic table. How many noble gases are there? What are their atomic symbols? 9. Compare the main characteristics of atoms, molecules and crystals. Make a table. 10. Draw pictures to illustrate an atom, an element and a molecule.

Compound crystal Common salt is made from sodium and chloride atoms bonded together.

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5. What is a chemical formula?

Oxygen molecule (O2)

Each element has its own chemical symbol: oxygen is O, calcium is Ca. To describe molecules, a chemical formula is used. A chemical formula consists of chemical symbols and numbers to indicate how many atoms of each element make up a molecule.

two oxygen atoms

For example, the formula for carbon monoxide is CO. This means that each molecule of carbon monoxide consists of one carbon atom joined to one oxygen atom. • Simple substances. The formula indicates the molecule of the substance. For example, O2 is the formula for the substance with molecules made up of two oxygen atoms joined together. F

O2

number of atoms

F

symbol for the element

• Compound substances. The formula indicates which elements make up the molecule. For example, a water molecule, H2O, consists of one atom of oxygen joined to two atoms of hydrogen. F

F

H2O

number of atoms

oxygen atom

F

F

symbols for each elements

• Crystals. Some elements form simple crystals. In this case, the chemical formula is the same as for the chemical symbol for the element. For example, carbon crystals: C.

hydrogen atoms

Water molecule (H2O)

• Compound crystals. The chemical formula indicates the elements and their proportions within the crystal. F

F

NaCl

chlorine atom

proportion of each F

F

symbols for elements

sodium atom

• Some chemical formulae are more complicated. For example, the formula for sodium sulphate is Na2SO4. It indicates that sodium sulphate consists of two sodium atoms, one sulphur atom and four oxygen atoms.

Sodium chloride molecule (Na Cl)

Activities 11. Copy the table and complete. Name

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Chemical formula

iron oxide

Fe2 O3

silver oxide

Ag2 O

aluminum oxide

Al2 O3

Atoms: name and number

12. Sucrose is the chemical name for sugar. Its formula is C12H22O11. a. How many elements make up this substance? b. What is the name of each element? c. How many atoms of each element are there in sucrose?

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6. Which elements can be found in nature? There are more than 110 elements in the Periodic Table, 92 are found in nature. All the others are man-made.

Universe hydrogen 83.9 %

Hydrogen and helium are the most abundant elements in the Universe. The stars are made up mainly of these two elements. Hydrogen (H2) is a gas. It makes up 83% of the Universe. It is found in the atmosphere, water, rocks… Helium (He) is a noble gas. It makes up 15.9% of matter in the Universe, but there is very little on Earth. other elements 0.2 %

helium 15.9 %

Living things hydrogen 63 %

others 0.6 %

Carbon, hydrogen, oxygen and nitrogen form 95% of all living things. Atoms of carbon combine with many other atoms to form a wide variety of molecules in living things. Some elements can be found both in living beings, in water and on the Earth’s crust. However, they form different compounds.

oxygen 25.5 %

nitrogen 1.4 %

Nitrogen (N2) is a gas formed by molecules. It is the most abundant gas in the Earth’s atmosphere. It is a basic compound of proteins. There is nitrogen in the soil.

oxygen 47 %

Oxygen (O2) is a gas formed by molecules. It is the most abundant element on Earth. It is found in the atmosphere in water, rocks and organic substances.

carbon 9.5 %

Earth’s crust silicon 28 % aluminium 7.9 %

Carbon (C) is the basis of all organic compounds in living things. It is found on the Earth’s crust as coal, graphite ...

others 1.69 %

iron 4.5 % calcium 3.5 % sodium 2.5 % potassium 2.5 %

carbon 0.19 % hydrogen 0.22 %

magnesium 2.2 %

Did you know that...? Living things are made up of about twenty elements.

Activities 13. Compare the pie charts. a. Which is the most homogeneous? In which is there more diversity? b. Ask questions about the charts: for example, Where is there more hydrogen? In the Universe or the Earth’s crust? Is there any silicon in living things? 14. Carbon is not the most abundant element in living things. Which element is?

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7. Why are elements important? In the Earth´s crust The most abundant elements which form the rocks and minerals of the Earth’s crust are silicon, aluminium, iron, magnesium and calcium. • Silicon (Si) is a solid, non-metal substance. It is generally found as a compound: the most common is quartz. It combines with oxygen to form silicates. • Aluminium (Al) is a soft, light metal. It is only found as a compound and is obtained from bauxite. Aluminium alloys are used to make aeroplanes, ships, etc. • Iron (Fe) is a grey metal. It is generally found as a compound. It combines with oxygen to form hematite and magnetite. Iron is present in your blood.

Magnesium is used in the composition of fireworks.

Did you know that...? Pure silicon is used to make microchips for computers.

• Magnesium (Mg) a silvery metal. It is found in minerals such as olivine. It burns very easily with a very bright, white flame. • Calcium (Ca) is a greyish white metal, found only in compounds. Calcium carbonate, (CaCO3), is found in seashells and egg shells. In sea water The most abundant elements in sea water are chlorine, sodium and potassium. • Chlorine (Cl) is a yellowish green gas at room temperature. It combines with metals to form salts. Chlorine is used to disinfect water in swimming pools. • Sodium (Na) is a soft, shiny metal. It is only found in compounds. It reacts easily with the oxygen in the air. Sodium chloride (NaCl) is common salt. • Potassium (K) is a soft, shiny metal. It is only found in compounds like potassium chloride (KCl). Sodium and potassium are also present in living things. They help muscle contraction and the functions of the nervous system.

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Water is disinfected with chlorine.

Activities 15. Which element can you find in: fireworks, sea shells, aeroplanes, and blood? 16. Classify the elements on this page in a table. Metal

Non metal

17. Describe an element. Your partner guesses which one. It is a soft, shiny metal. It is found in common salt.

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Hands on Writing a fact file: Elements Research an element from the Periodic Table. Then, write up your fact file. Follow this outline to help you.

1. Chemical composition. Choose an element. What is its atomic symbol? Draw the atom. What is its chemical formula?

Some interesting elements: copper, iron, phosphorus, sulphur, fluorine, iodine.

4. Why it is important. Is it important in living things, or in the Earth’s crust? Give some facts and examples.

2. Description. Write a physical description of the substance. Is it solid, liquid or gas? Is it a metal or a non-metal?

5. Some important uses. What is this element or its compounds used for? What other forms does it have?

3. Where it is found in nature. Is it found as a simple substance or a compound substance? Is it abundant or rare?

Calcium Fact File Calcium, Ca has an atomic number of 20. Description

Calcium atom

Calcium is a soft, grey metal. Where it is found in nature Calcium is not found as an element in nature. It is usually found in rocks like limestone or gypsum. Why it is important Calcium is the fifth most abundant element in the Earth’s crust. It is also essential for living things. It is the most common mineral in the human body. 99 % of this is found in bones and teeth. Calcium carbonate (CaCO3) is the main component of seashells, egg shells and snail shells. Some important uses It is used as an antacid for stomach pains.

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Activities 25. Study the diagrams. Different atoms are shown in different colours.

18. Copy and label this atom: nucleus protons neutrons electrons

19. Each of these formulas represents a gaseous substance: (CO) carbon monoxide, (NO) nitrogen oxide, (C4H10) butane.

A

B

C

D

Explain the meaning of each formula. 20. Write the formula for a substance which contains two atoms of hydrogen, one atom of sulphur, and four atoms of oxygen. 21. Carbon monoxide is a gas: CO. Lead is a solid, heavy metal. Could these substances be found as molecules or as crystals? 22. What is the difference between an atom and a molecule?

a. Which drawings correspond to elements? b. Which drawings correspond to compounds? Explain your answers. c. Can you see any molecules? How many atoms does each have? 26. Copy and complete the table. Element

23. Use the Periodic Table to make a list of the elements that are most abundant in: a. The Universe.

b. The Earth’s crust.

24. Copy and complete the summary for each element.

Compound

Copper (Cu) Sulphur dioxide (SO2) Sulphuric acid (H2SO4) Helium (He)

Elements in nature

Nitrogen (N2)

The Earth’s crust

In sea water

27. Copy and complete the table. Silicon compound / formula

Chlorine

water (H20)

Si

sodium hydroxide (NaOH)

non-metal

sodium sulphate (Na2SO4)

It is in quartz. It forms silicates.

calcium carbonate (CaCO3)

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elements / number of atoms hydrogen: 2 oxygen: 1

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ATOMS AND ELEMENTS

What should you know? Atoms and elements

Atoms are the smallest particles of a chemical element. They are made up of a nucleus with protons and neutrons, and electrons which orbit the nucleus. • Matter is made up of atoms. • Elements are formed by equal atoms. • Compounds consist of two or more different atoms. There are more than one hundred different elements. They are classified in the Periodic Table of Elements.

Substances and formulas

Atoms form different types of substances: • Monoatomic: the noble gases. • Molecules: the union of two or more atoms. – Simple molecules: formed by identical atoms: gases (O2, N2, H2) – Compound molecules: formed by different atoms: compounds in gas or liquid form (H2O, CO2). • Crystals: many atoms joined together in an organised structure. – Simple crystals: formed by identical atoms. Example: metals. – Compound crystals: formed by different atoms. Example: solid substances like sodium chloride (NaCl).

Elements in nature

• Hydrogen. A gas formed by molecules (H2). It is the most abundant gas in the Universe. • Helium. A gas formed by atoms (He). It is the second most abundant gas in the Universe. • Nitrogen. A gas formed by molecules (N2). It is the most abundant gas in the Earth’s atmosphere. • Oxygen. A gas formed by molecules (O2). It is the most abundant element on Earth, and the second most abundant in the atmosphere. • Carbon is the basis of organic compounds. • Silicon is only found as a compound in nature. It is the main component of silicates. • Aluminium, iron, magnesium and calcium are metals which are abundant in minerals and rocks. • Chlorine, magnesium, sodium and potassium dissolve in water. They make up the ‘salt’ in sea water.

14

Universe

Living things

Earth’s crust

Projects for living things. Why?

• Why do we use fertilizers with nitrogen? • Where does nitrogen in the soil come from?

• Can plants live in soil without nitrogen?

WEB TASK: Research the world of nanotechnology.

INVESTIGATE: Nitrogen in soil is very important

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Vocabulary 1

The Universe

asteroids

rocky bodies which orbit the stars.

astronomical unit the distance from the Earth to the Sun: approximately 150 million kilometres. galaxies a vast collection of stars, dust and gases, held together by gravitational attraction. geocentric theory proposed that the Earth was the centre of the Universe. heliocentric theory proposed that the Sun was at the centre of the Universe. light-year the distance light travels in one year: about 9.5 trillion km. Milky Way the galaxy where our Solar System is. orbit a curved path which a celestial body follows in its revolution around another celestial body. 2

Planet Earth

atmosphere the layer of gases which envelops the Earth. Nitrogen and oxygen are the most abundant. biosphere the part of the Earth’s surface, sea and air that is inhabited by living things. core the centre of the Earth, below the mantle. Its temperature is over 4,000°C. crust the outer layer of the Earth’s surface. It is divided into continental crust and oceanic crust. equinox the time of the year when day and night are exactly the same length. geosphere the solid part of the Earth which includes the lithosphere, the mantle and the core. hydrosphere

all the water on Earth.

lithosphere the upper 100 km of the geosphere. It is is made up of the crust and the upper mantle. lunar eclipse when the Moon passes behind the Earth, so the Earth prevents sunlight from reaching the Moon. mantle the middle layer of the Earth, below the crust. It is made up of rock. The temperature is from 1,000 to 4,000ºC, so some areas are melted rock. revolution the elliptical path taken by one body around another. The Earth revolves around the Sun. rotation the Earth rotates on its axis. The axis is tilted 23.5 degrees. This rotation creates day and night.

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solar eclipse when the Moon passes between the Sun and the Earth, and blocks off the sunlight. water cycle the movement of water around, over, and through the Earth: evaporation, condensation, precipitation, surface runoff and infiltration. 3

Living things

autotrophs living things which produce the organic substances they need from inorganic substances. Plants, algae and some bacteria are autotrophs. cell membrane the outer covering of a cell. The cell membrane keeps the cell together and controls what passes in and out of it. chloroplasts organelles with a green pigment, chlorophyll, which absorbs the Sun’s energy to elaborate organic matter during photosynthesis. cytoplasm the inside of a cell where many of the chemical reactions take place. eukaryotic cells cells which have a nucleus, separated from the cytoplasm by the nuclear membrane. heterotrophs living things which obtain nutrition from organic matter which is already elaborated. Animals, fungi, and all protozoa are heterotrophs. inorganic substances things which contain no carbon. They are present in living things and non-living things: water and mineral salts. organelles small structures in the cytoplasm responsible for respiration, making and storing nutrients, etc. organic substances substances exclusive to living things. Carbon is the principal element. Organic substances include: glucides, lipids, proteins and nucleic acids. nutrition all the processes which enable living things to obtain the energy and matter they need to live. photosynthesis the process through which plants obtain nutrition. prokaryotic cells cells with no nucleus or nuclear membrane. Genetic material is dispersed throughout the cytoplasm. They are simpler than eukaryotic cells. species the first level of classification for living things. A group of living things which are physically similar. They reproduce and usually have fertile descendants.

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Invertebrates

annelids invertebrates with soft, cylindrical bodies divided into segments, with organs in each segment. Most breathe through gills. arthropods the largest and most varied group of living things: more than one million species. They live in sea water, fresh water and on land. cephalopods a group of molluscs. They have tentacles, but no shell. For example: squid, cuttlefish and octopus. cnidaria jellyfish, corals and sea anemones. They have a soft body, with only one opening and a mouth surrounded by tentacles. crustaceans a group of arthropods with 10 legs, with usually an aquatic habitat. For example: lobster or crab. echinoderms invertebrate animals which live on the sea bed. For example, sea urchins, starfish and sea cucumbers. gastropods a group of molluscs. Gastropods have a spiral-shaped shell with a single valve. For example, snails, sea snails and slugs. Slugs have no shell.

poikilotherms cold-blooded animals. They cannot regulate their body temperature, so are warm or cold depending on the environment. reptiles vertebrate animals with bodies covered with hard scales. They are poikilothermal and most of them are oviparous and carnivorous. viviparous animals that give birth to live young. Development starts in the mother’s body. The babies feed on the mother’s milk. 6

The plant and fungi kingdoms

angiosperm flowering plants which have seeds inside a real fruit. dispersal a stage of plant reproduction. The ripe fruit falls off the plant or releases the seeds. ferns small non-flowering plants. Ferns are vascular. They have roots, stems, and leaves called fronds.

molluscs a group of invertebrate animals with a soft body divided into head, body mass and foot. For example, squid, mussels, oysters, slugs and snails.

fertilisation a stage of plant reproduction. Pollen reaches the stigma, penetrates it, and fertilises the ovules inside the ovary.

myriapods a group of arthropods with worm-like bodies and many legs. They are terrestrial. For example, centipede and scolopendra.

fungi have eukaryotic cells and are heterotrophic. Fungi are made up of hyphae, which group together to form the mycelium.

oviparous animals that lay eggs. Eggs are laid by the female and develop outside the body.

germination the last stage of plant reproduction. Seeds germinate producing a tiny shoot and root.

platyhelminths invertebrates with long, flat, soft bodies. They have neither legs nor respiratory or digestive systems. Many are parasites. polyp cnidaria bodies shaped like a tube with the opening at the top. For example, corals and sea anemones. porifera invertebrate animals without organs. Sponges belong to this group. 5

Vertebrates

amphibians vertebrate animals. Their skin is moist and has no covering. They have four legs and are poikilothermal. They undergo metamorphosis. homeotherms warm-blooded animals: capable of keeping their body temperature constant.

gymnosperm one kind of flowering plant. They have seeds inside a false fruit, like a pinecone. mosses small, non-flowering plants. They are nonvascular. They have no true roots, stems or leaves. pollination the first stage of plant reproduction. Wind and insects transport pollen from one flower to another. stomata

microscopic pores on the underside of a leaf.

transpiration process by which excess water is expelled through leaf stomata in the form of water vapour. vascular plants with conductor vessels to distribute water and nutrients. yeasts unicellular fungi. Some types are used to make bread, wine, beer, etc. 7

The simplest living things

mammals a group of vertebrate animals. Their bodies are covered with hair or fur. They are homeothermal and have mammary glands.

algae unicellular or multicellular autotrophs. They live in salt and fresh water.

ovoviviparous animals that are born from an egg. The egg develops inside the female.

bacteria microscopic, prokaryotic organisms. They belong to the Monera kingdom.

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a group of protozoa with hair-like organs.

flagellates one of the groups of protozoa. They move with a flagellum (tail). protoctist unicellular and multicellular living things. They are eukaryotes and have no tissues. The Protoctist kingdom includes protozoa and algae.

9

The hydrosphere

condensation the process in which water vapour changes to liquid. currents movement of large bodies of water by prevailing winds.

protozoa unicellular and heterotrophic living things. Some are parasites, and cause illnesses.

evaporation the process of the water cycle in which liquid water changes to a gas (water vapour).

rhizopods protozoa with pseudopods (projections of the cell cytoplasm).

evapotranspiration when water evaporates into the atmosphere from the leaves and stems of plants.

saprophytes organisms which live on dead or decomposing matter. They transform organic substances into inorganic substances.

groundwater

sporozoa

surface runoff when the movement of surface water across the land forms rivers and streams.

a group of protozoa that cannot move.

vaccines contain dead or weakened microorganisms from a specific illness. They teach the body how to fight an illness. 8

The Earth’s atmosphere

acid rain rain with dissolved pollutants such as sulphur dioxide and nitrogen oxide. climate describes the characteristic pattern of weather in an area, over a long period of time. global warming in the last century, the atmosphere has warmed between 0.5 and 0.9ºC on average. greenhouse effect a natural phenomenon, essential for keeping the temperatures on Earth suitable for life. CO2 in the atmosphere acts like the glass walls of a greenhouse. It traps the heat and prevents it from returning into space.

water located beneath the ground.

infiltration surface water penetrates into the ground. This occurs more easily if the ground is porous.

tides the rise and fall of water levels due to gravitational attraction of the Moon and the Sun. waves occur on the surface of water, caused by the wind. Wave action causes cliff erosion and creates beaches. 10

Minerals

hardness measures how a mineral reacts to being scratched. impurities small amounts of other substances found in minerals. These can change some mineral properties. lustre refers to the way minerals reflect light. It can be metallic, or non-metalic. mixtures are made up of different substances of varying sizes, shapes and colours.

ionosphere the highest and thickest layer of the atmosphere.

Mohs Scale of Hardness classifies minerals by hardness. One is soft. Ten is the hardest.

mesosphere a layer of the atmosphere about 40 km thick. It contains clouds of ice and dust.

non-silicates minerals which contain no silicon: native elements, oxides, sulphides, carbonates and halides.

meteorology the study of different atmospheric variables to make weather predictions. ozone (O3) a gas which exists throughout the atmosphere, mainly concentrated in the stratosphere. It makes up the ozone layer. stratosphere a layer of the atmosphere about 30 km thick. There is an increase in temperature from –70ºC at its lower limit, to 0ºC at its higher limit.

silicates the most abundant minerals on Earth. They are made up of silicon and oxygen. Some common silicates are quartz and feldspar. streak the colour of the powder left when minerals are scratched. 11

Rocks

troposphere a very thin layer which represents 80% of the total mass of the atmosphere. Aeroplanes fly at this level. It is where the greenhouse effect is produced.

cementation the process by which sedimentary rock is formed from sediments glued together.

weather describes the state of atmospheric conditions at a certain place, over a short period of time.

compaction the weight of layers of sediments which reduces the spaces between the fragments and squeezes out the water. As a result, salt crystals are formed.

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erosion fragments of rocks are picked up and transported by running water, glaciers, or wind. igneous rocks rocks formed from cooled magma. metamorphic rocks rocks formed from other rocks by the effects of heat or pressure. metamorphism a slow process in which temperature and pressure change parent rock into metamorphic rock. organic sedimentary rocks made up of organic material, fossils. There are two kinds: oil and coal. plutonic (intrusive) rocks rocks formed as magma cools slowly under the ground over thousands of years. rock cycle the processes which form, change and recycle rocks over millions of years. sedimentary rocks rocks formed by the accumulation and compaction of sediment, for example, clay, sand or rock fragments. volcanic (extrusive) rocks rocks formed as lava cools rapidly on the Earth’s surface. weathering atmospheric phenomena (changes in temperature, rain, etc.), or the activities of plants and animals which break up rocks. 12

Matter and its properties

base units used to measure length, mass, time, etc. capacity the amount of liquid a container can hold when it is full. Capacity is measured in litres (L). degrees Celsius a scale used to measure temperature. 0ºC equals 273.15K or 32ºF. density the relationship between the mass and the volume of a body. Measured in kg/m3 or g/cm3. derived units obtained from a combination of the base units. They are used to measure surface area, volume, speed, density, etc. International System of Units (SI) a system which defines the base and derived units required to measure the properties of matter. kelvin one of the scales of the International System of Units that is used to measure temperature. 0 K equals –273.15ºC and –459.67ºF. mass the amount of matter in a body. Mass is measured in kilograms (kg). matter all objects that take up space, and have mass. Everything around us is made of matter. surface area the extension of a body in two dimensions, measured in square metres (m2). volume the amount of space matter occupies. Volume is measured in cubic metres (m3).

13

Everything is matter

chemical compound a substance containing two or more elements joined up. compressibility a property which measures the difficulty of matter to be compressed. fusion the process by which a solid changes into a liquid. heterogeneous a mixture of substances where more than one part is distinguishable. homogeneous a substance which is uniform in structure and composition. recycle to transform used materials into new materials. regressive sublimation the process by which a gas changes directly into a solid. solidification the process by which a liquid is cooled and changes to a solid. solute in a mixture, the dissolved substance. solution any homogeneous mixture. solvent in a mixture, the part where the substance is dissolved. sublimation the process by which a solid changes into a gas, without first becoming a liquid. vaporisation when a liquid evaporates into a gas. 14

Atoms and elements

atom the smallest particle of matter which can exist alone. It is made up of a nucleus with protons and neutrons, and electrons. atomic number the number of protons in the nucleus of an atom. This number is different for each atom. chemical formula symbols which indicate how many atoms make up a molecule. crystals consist of atoms or molecules arranged in a regular, organised structure. electrons extremely small particles that orbit the nucleus. They have a negative charge (–) and are attracted to the positively charged protons in the nucleus. element a substance that contains just one type of atom. It cannot be broken down into anything simpler by chemical reaction. molecules two or more atoms joined together. neutrons particles in the nucleus which have no charge. periodic table of elements a table in which all elements are grouped with similar elements, with their symbol and atomic number. protons particles in the atom’s nucleus, which have a positive charge.

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Key language CLASSIFYING Non-silicates There are

are classified into two groups of minerals.

five groups.

How many groups How are

of non-silicates minerals

Five. Into two groups.

are there? classified?

COMPARING Planets are The closest star

bigger than to Earth is the Sun.

Are planets

bigger than

other celestial bodies.

other celestial bodies?

Ocean trenches are

the deepest areas The largest plains

of on

Where

are the largest

plains on the planet?

Ferns Flowering plants

the oceans. the planet are under the oceans.

are

bigger than mosses. more complex.

Which group is bigger, ferns or mosses?

Ferns.

The higher The higher

a place is, the altitude,

Where is it colder?

The higher a place is,

Talc

is softer than

apatite.

Is

talc

harder than

the colder the lower

it will be. the density of the air.

the colder

apatite?

That box is

four times bigger than this one.

Why does oil float on water?

Because it is less dense.

Hydrogen and helium are

the most abundant

elements

Which are

the most abundant

elements?

it will be.

No, it isn’t.

in the Universe.

DESCRIBING The Sun Asteroids

consists mainly of are

What does the Sun consist of? Water There

exists are

How many states does water exist in?

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hydrogen and helium. rocky objects.

What are asteroids? in three states. submarine volcanoes in the oceans.

Are there volcanoes in the oceans?

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DESCRIBING A bacteria

does not have

an organised nucleus.

Does

a bacteria

have an organised nucleus? No, it doesn’t.

Water Water

is absorbs heat.

a powerful solvent.

What

are two properties of water? Cohesion and adhesion.

Petroleum Mica

is can be scratched

Is How hard

petroleum a mineral? is talc?

A pure substance

a rock. with a fingernail. No, it’s a rock. It has a hardness of 1 on the Mohs scale.

has

Is sea water a homogeneous mixture?

only one component. Yes, it is.

Calcium

is

a greyish white metal.

What is potassium like?

It is a soft, shiny metal. DESCRIBING A PROCESS

When minerals dissolve in water, raw sap When pollen penetrates the stigma, ovules

When

are

ovules

Igneous rocks

How

are

is produced. are fertilised.

fertilised?

When pollen penetrates the stigma.

are formed as a result of

igneons rocks

When paper When you mix

formed?

is burned, sand and water,

the solidification of magma.

By the effects of heart and pressure.

it changes into you get

ashes. a heterogeneous mixture.

When does sublimation occur? When a solid changes directly into a gas. EXPRESSING FACTS Living things Inorganic substances

What Do

feed and reproduce. do not contain

do living things inorganic substances contain

The Monera kingdom Most bacteria

carbon.

do? carbon?

contains do not produce

They reproduce. No, they don’t.

unicellular organisms. their own food.

EXPRESSING AMOUNTS The Earth’s atmosphere

is about 800 km

high.

How high is the atmosphere?

About 800 km

high.

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EXPRESSING AMOUNTS 68.7% of fresh water

is found

in lakes.

How much salt What percentage of fresh water

is there in sea water? About 35 grams. is there on the Earth? Only 3%.

EXPRESSING CAUSE AND RESULT Water exists in three states The Earth looks blue

due to because of

temperature variations. the water on its surface.

Why does the Earth

look blue?

Because of the water.

They undergo metamorphosis.

As a result,

they develop lungs.

How do amphibians develop lungs?

As a result of

metamorphosis

EXPRESSING CONTRAST Some arthropods Most gastropods

are have

carnivores, a shell,

but but

others are herbivores. slugs don’t.

Do all cephalopods have a shell?

Are all arthropods carnivores?

Most fish are covered with scales.

However,

Do all fish have scales?

Most do. However,

a shark’s skin has denticles. sharks have denticles.

EXPRESSING DIRECTION Water filters Waves transport sand

into along the coast and

the ground. out to sea.

Where does water flow?

To the sea, and

into the ground.

EXPRESSING PURPOSE Water is necessary Living things need glucose

to transport to get

all other substances. energy.

Why is water necessary? Why do living things need glucose?

To transport To get

substances. energy.

Reptiles have hard scales

to keep

them warm.

Why do reptiles have hard scales? Ceramic materials

are used

for tiles and bricks.

How are rocks used?

Which rock is used for roofs? GIVING INSTRUCTIONS

Study Research

166

the constellations. more about them on the Internet.

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GIVING INSTRUCTIONS Label

each jar.

Observe

the samples.

INDICATING LOCATION Magnesium

is found in

minerals.

Where

is

magnesium

found?

In minerals.

MAKING GENERALISATIONS Most sponges Some molluscs

live have

in the sea. no shell.

Where

do

most sponges

All Most

plants gymnosperms

Do

have are

all plants have roots?

Most rocks Solutions

contain can be

live?

roots. evergreens.

Are

all gymnosperms evergreens?

a mixture of minerals. solid, liquid or gaseous.

How many states of matter

are there?

Three.

MAKING IMPERSONAL STATEMENTS Systems

are made up of

several organs.

What

are systems

made up of?

Some bodies

What

are divided

are

their bodies

Some rocks Sedimentary rocks

How

are

rocks

The volume of a liquid A thermometer

How

is

into segments.

like?

can be broken into are found

irregular shapes. in strata.

classified?

three main classes.

can be calculated is used

surface area

A series of segments.

measured?

Into

by measuring the container. to measure temperature. In square metres (m2).

MEASURING The court Density is measured

measures 18 by 15 metres. in kilograms per cubic metre (Kg/m3).

How cold is that? How is density measured?

Minus 273.15ºC. In kilograms per cubic metre.

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Essential Natural Science 1 is a collective work, conceived, designed and created by the Secondary Education department at Santillana, under the supervision of ENRIQUE JUAN REDAL, ANTONIO BRANDI and MICHELE C. GUERRINI Content writers: Concha Barreiro, Marcos Blanco, Antonio Delgado, Belén Garrido, Pilar de Luis, Miguel Ángel Madrid, Ignacio Meléndez, Margarita Montes and Cristina Zarzuelo Content consultants: Kevin Salvage and Carmen Rengel Language specialists: María José Sánchez (Key language), María Rosa Batlle, Giselle Dubois, Paul House, Kate Marriage, Beatriz Papaseit and Ana María Pons English editors: Sheila Tourle, Sheila Klaiber, Kirsten Ruiz-McOmish, Rebecca Adlard and Patricia Gómez Student CD: Vocabulary organiser: Antonio Delgado Web tasks: Jeannette West Art director: José Crespo Design coordinator: Rosa Marín Design Team: Cover: Martín León-Barreto Interior: Manuel García, Alfredo Mateo Coordinator, design development: Javier Tejeda Design development: José Luis García and Raúl de Andrés Technical director: Ángel García Encinar Technical coordinator: Marisa Valbuena Layout: Alfredo Mateos, Javier Pulido Artwork coordinator: Carlos Aguilera Illustrations: alademoscail-lustració, Digitalartis, Marcelo Pérez, Pere Luis León Research and photographic selection: Amparo Rodríguez Photographs:

A. Toimil; A. Toril; A. Viñas; Algar; C. Díez; C. Jiménez; C. Roca; C. Suárez; C. Valderrábano e I. Hernández; D. Lezama; D. López; F. de Santiago; F. Gracia; F. Ontañón; F. Orte; F. Po; G. Rodríguez; GARCÍA-PELAYO/Juancho; I. Rovira; I. Sabater; J. C. Martínez; J. C. Muñoz/’Instituto Geológico y Minero de España’; J. Escandell.com; J. I. Medina; J. Jaime; J. L. G. Grande; J. Lucas; J. M. Borrero; J. M.ª Barres; J. M.ª Escudero; J. Ruiz; J. V. Resino; Juan M. Ruiz; Krauel; L. M. Iglesias; M. Izquierdo; M.ª A. Ferrándiz; Michele di Piccione; O. Torres; P. Anca; P. Esgueva; P. López; P. Nadal; Prats i Camps; R. Antunes; R. Vela; Roca-Madariaga; S. Cid; S. Padura; Sánchez-Durán; X. Andrés; A. G. E. FOTOSTOCK/K. H. Jacobi, Andrew Syred, Tom Servais, Nacho Moro, Marevision, Dan Suzio, Jim Zipp, PIXTAL, CNRI, Dennis Kunkel, SPL, Claude Nuridsany & Marie Perennou, SCUBAZOO/Matthew Oldfield, Science Photo Library, Detlev Van Ravenswaay, Science Museum/SSPL, Dr. Gary D. Gaugler, Dr M. A. Ansary/SPL, Sinclair Stammers, Herman Eisenbeiss, Susumu Nishinaga, SCIENCE PHOTO LIBRARY, James Cavallini, CINTRACT Romain, Eye of Science; A.S.A./Minden Pictures/FOTO NATURA/Armin Maywald; ABB FOTÓGRAFOS/F. Baixeras; ACTIVIDADES Y SERVICIOS FOTOGRÁFICOS/J. Latova; ARIAS FORMATO PROFESIONAL/A. Arias; COMSTOCK; CONTIFOTO/François Merlet, VISA REPORTAGE/X. Desmier; COVER/POPPERFOTO; COVER/SYGMA/Dan Bool; COVER/CORBIS/Papilio/Bryan Knox, Tim Davis, EPA/Irwan; DIGITAL BANK; DIGITALVISION; EFE/AP PHOTO/The Miami Herald/Ron Magill, EPA PHOTO/FEATURECHINA, Alfredo Aldai, César Borja, M. Martí, M. Riopa, AP PHOTO/I. UNDATED FILE PHOTO, AP PHOTO/NASA/EIT, SIPA SANTÉ/BN/SIPA ICONO; EFE/SIPA-PRESS/Lambert, Becker, David Howells, Dirk Heinrich, F. Durand, Gerald Buthaud, Hulot, Leonide Principe, Pinson, Romuald Meigneux, S. Corp., SEA WORLD (GATLEY); FOCOLTONE; FOTONONSTOP; GALICIA EDITORIAL/Miguel Villar; GETTY IMAGES SALES SPAIN; HIGHRES PRESS STOCK/AbleStock.com; I. Preysler; JOHN FOXX IMAGES; LOBO PRODUCCIONES / C. Sanz; MICROS/J. M. Blanco; MELBA AGENCY; NASA/Provided by the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE, NASA, ESA and A. Nota (STScI/ESA), Credit Image created by Reto Stockli with the help of Alan Nelson, under the leadership of Fritz Hasler; PAISAJES ESPAÑOLES; PHOTODISC; SEIS X SEIS; STOCKBYTE; BUREAU INTERNATIONAL DES POIDS ET MESURE; C. Brito/J. Núñez; Calvin Hamilton; cortesía IBM; FUNDACIÓ ‘LA CAIXA’/Colección Fundació ‘La Caixa’; I. Nieva; INSTITUTO GEOLÓGICO Y MINERO DE ESPAÑA; INSTITUTO NACIONAL DE METEOROLOGÍA, MADRID; M. Falagán; M. Vives; MATTON-BILD; MUSEO CAPITOLINO, ROMA; Parque Nacional Marítimo-Terrestre de las Islas Atlánticas, Galicia/Roberto Castiñeira; S. Matellano; SERIDEC PHOTOIMAGENES CD/DIGITALVISION; T. Grence; ARCHIVO SANTILLANA

The publishers would like to express their gratitude to the following teachers for their insightful comments and useful suggestions throughout the preparation of Essential Natural Science. Carlos Álvarez Santos, Silvia Durán, José Ramón Noya, Maureen Vidal Gafford

© 2008 by Santillana Educación, S. L. / Richmond Publishing Torrelaguna, 60. 28043 Madrid Richmond Publishing is an imprint of Santillana Educación, S. L.

Richmond Publishing 58 St Aldates Oxford OX1 1ST

PRINTED IN SPAIN Printed in Spain ISBN: 978-84-294-2222-1 CP: 877306 D.L.:

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