Complete Science for Cambridge IGCSE

Endorsed by University of Cambridge International Examinations

Complete

Science

New edi t with tea ions ching support

for Cambridge IGCSE

Complete Biology, Chemistry and Physics are now comprehensive science courses – complete with teaching support and revision materials.

What do you get with the new Complete Science? ✓ A challenging IGCSE programme that will stretch your students and develop their critical thinking skills, while still supporting your lower-ability pupils ✓ Brand new teaching support – in print and digital – that you can easily customise to make sure you teach exactly what you want ✓ Flexible learning options with a free student CD-ROM designed to strengthen exam preparedness ✓ Up-to-date and internationally-focused content endorsed for the newest Cambridge IGCSE syllabus ✓ Support for your EAL students with page-by-page vocabulary support

Look inside to see how you can use the new Complete Science

2

Ways to teach with Complete Science

Step 2 – Exploit the digital resources

We’ve developed Complete Science for international science teachers and it’s designed to meet your core priorities:

Download a ready-made PowerPoint and customise it with your own data, images and web links for an effective and hassle-free lesson

✓ Quick and easy planning which doesn’t compromise lesson quality ✓ Flexible, straightforward resources that let you choose how you use them

Find the digitised version of any of the print worksheets in the Teacher’s book and adapt it so it works exactly how you want

✓ Thorough and comprehensive material that will fully prepare students for exams ✓ Clear, uncomplicated language with support for EAL students ✓ Exact match to the most recent Cambridge IGCSE syllabus

Refer to the syllabus matching grid to make sure you’re covering everything in the most recent Cambridge syllabus

Step 1 – Use the Student Books Clear, uncomplicated language ORGANISMS AND THEIR ENVIRONMENT with highlighted keywords to support your EAL 4.3 Feeding relationships: pyramids of students

numbers, biomass and energy

OBJECTIVES

■

To be able to describe pyramids of numbers, biomass and energy To understand how data can be gathered to make ecological pyramids

Pyramids of numbers Look at the food chain on page 248. Two things should be clear: ■ The organisms tend to get bigger moving along the food chain. Predators, such as the cat, need to be large enough to overcome their prey, such as the mouse. ■ Energy is ‘lost’ as heat on moving from one trophic level to the next, so an animal to the right of a food chain needs to eat several organisms ‘below’ it in order to obtain enough energy. For example, a rabbit eats many blades of grass.

Food chains and food webs provide qualitative information about an ecosystem – they show which organism feeds on which other organism. How do we show quantitative information, for example how many predators can be supported by a certain number of plants at the start of the chain? We can use a pyramid of numbers or a pyramid of biomass, as shown in the diagram below.

ORGANISMS AND THEIR ENVIRONMENT

biomass’ and the pyramid would be inverted. To overcome this difficulty a pyramid of energy can be constructed. This measures the amount of energy flowing through an ecosystem over a period of time. The time period is usually a year, since this takes into account the changing rates of growth and reproduction in different seasons. It is even possible to add an extra base layer to the pyramid of energy representing the solar energy entering that particular ecosystem.

To construct a pyramid of numbers or of biomass, organisms must be captured, counted and (perhaps) weighed. This is done on a sample (a small number) of the organisms in an ecosystem. Counting every individual organism in a habitat would be extremely time-consuming and could considerably damage the environment.

A pyramid of biomass describes how much biomass is present in a habitat at the time the sample is taken. This can be misleading, because different feeding levels may contain organisms that reproduce, and so replace themselves, at different rates. For example, grass in a field would replace itself more quickly than cattle feeding on the grass, so when the pyramid of biomass is constructed there would be more ‘cattle biomass’ than ‘grass

Physics

Step 3 – Help students revise S Pyramid of energy: energy values are expressed as units of energy per unit area per unit time (e.g. kJ per m2 per year)

IGCSE Revision guide: Physics

Wing nut

Refresh students’ memories and focus their attention with the clearly outlined learning objectives

Wire

The sample should give an accurate estimate of the total population size. To do this: ■ The sampling must be random to avoid any bias. For

Metal or wooden frame

20 cm 20 cm

example, it is tempting to collect a large number of organisms, by looking for the areas where they are most common. To avoid this, the possible sampling

Note 1 The number of organisms at any trophic level is represented by the length (or the area) of a rectangle. 2 Moving up the pyramid, the number of organisms generally decreases, but the size of each individual increases.

Complete Chemistry for Cambridge IGCSE Teacher’s Resource Kit CD-ROM

Metals also have free electrons in their structure which gain kinetic energy at the hot end of the bar. These free electrons pass on their kinetic energy through collisions with other electrons and metal atoms as they randomly diffuse through the metal. In this way, energy (heat) is conducted from the hot end of the bar to the cold end.

GATHERING DATA FOR ECOLOGICAL PYRAMIDS

Pyramids of energy

Pyramid of numbers – a diagrammatic representation of the number of different organisms at each trophic level in an ecosystem at any one time

Distribute the mock IGCSE questions, so students get used to answering real questions taken from past exams

Biology

1m

■

Chemistry

1m

using random number generators on a computer.

Small carnivore

■ The sample must be the right size so that any

Herbivore

‘rogue’ results can be eliminated. For example, a

Producers

single sample might be taken from a bare patch of earth, whereas all other sites are covered with

But wait!

An experiment to show that water is a poor conductor of heat

KEY IDEAS

boiling tube

convection

bunsen burner

laid on the ground and the number of organisms inside it is counted. copper bar

A quadrat is used most commonly for estimating the size of plant populations, but may also be valuable for the study of populations of sessile or slow-moving animals (e.g. limpets).

ice

blob of wax drawing pin

Bunsen flame

vegetation. The single sample from the bare patch should not be ignored, but its effects on the results will be lessened if another nine samples are taken.

Pyramid of biomass – which represents the biomass (number of individuals × mass of each individual) at each trophic level at any one time. This should solve the scale and inversion problems of the pyramid of numbers.

Sampling plants and sessile animals

Tawny owl

Oak tree So …

Bird lice Tawny owl

Help pupils more effectively absorb information via the concise and focused explanations

Once the organisms in a sample have been identified and counted, the population size can be estimated. For example, if 10 quadrats gave a mean of 8 plants per quadrat, and each quadrat is one-hundredth of the area of the total site, then the total plant population in that

Blue tits Insect larvae

b Pyramids may be inverted, particularly if the producer is very large (e.g. an oak tree) or parasites feed on the consumers (e.g. bird lice on an owl).

Ice is trapped at the bottom of the boiling tube with a piece of metal gauze. When the water at the top of the boiling tube is heated strongly, it boils. The ice at the bottom of the tube does not melt. This shows that water is a poor conductor of heat. However, if the ice is allowed to float normally, it melts quickly when the water is heated at the bottom of the test tube. This is because the water molecules can move, so the water heats by convection.

A mean value can then be used.

Bird lice

Problems a The range of numbers may be enormous – 500 000 grass plants may only support a single top carnivore – so that drawing the pyramid to scale may be very difficult.

area is 8  100  800.

Biomass expressed as units of mass per unit area (e.g. kg per m2)

If a copper bar is heated at one end with a Bunsen flame, the drawing pins fall off one by one, beginning with the pin closest to the Bunsen flame. This is because as the metal conducts the heat from the hot end of the bar to the cold end, each of the blobs of wax melts in turn.

cold end

Complete Biology for Cambridge IGCSE

Materials that are poor conductors are called insulators. For example, air is an insulator.

hot end

electrons with the lowest vibrational energy

Insect larvae

metal ions

S Ecological pyramids represent numerical relationships between successive trophic levels. The pyramid of biomass is useful because the biomass gives a good idea of how much energy is passed on to the next trophic level.

913876_IGCSE_BIO_CH04.indd 252

Water, like other liquids and non-metal solids, is a poor conductor of heat energy because its molecules do not have free electrons to easily pass on their kinetic energy to their neighbours, so the heat can only be transmitted through the vibration of the particles. Gases are very poor conductors of heat energy because their molecules are very far apart so kinetic energy cannot be transmitted from one molecule to another.

Blue tits Oak tree

252

Use the diagrams and visual aids to make sure that everyone understands, supporting all types of learners

metal gauze

✓ All objects emit and absorb heat through infrared radiation ✓ Black surfaces are the best emitters and the best absorbers of infrared radiation ✓ Silver surfaces are the worst emitters and the worst absorbers of infrared radiation

An experiment to show that copper is a good conductor of heat

 A quadrat is a square frame made of wood or metal. It is simply

boiling water

✓ Heat is transferred in solids by the vibrations of the molecules. This is conduction ✓ Heat is transferred in liquids and gases by the movement of the molecules. This is

Conduction

sites can each be given a number and then chosen

Top carnivore

2.3 Transfer of thermal energy

09/10/2010 14:51:39

Flip to this back of this leaflet to see a linked practical activity from the Teacher’s Resour ce Kit

Case studies aid comprehension and are linked to practicals in the Teacher’s Kits - helping students put theories into practice

913876_IGCSE_BIO_CH04.indd 253

253 Flip to the section questions to further consolidate learning and help students measure their progress – these questions are also on the Student CD-ROM

Want to help students gauge their learning? Use the summative tests for each unit on the Student CD-ROM for an instant progress-check.

09/10/2010 14:51:41

Remember to support pupils with the highlighted vocabulary words which could challenge your EAL students

electrons with the most vibrational energy

Metal atoms that have lost their free electrons are called ions. Sometimes metals are described as a lattice of metal ions in a “sea” of free electrons. Other solids are not usually good conductors of heat because they do not have free electrons to transfer heat energy from one molecule to another. At the hot end of the metal bar, the ions gain energy and vibrate faster. The ions in a metal are close together and so these ions pass on their vibrations to neighbouring ions, which in turn start to vibrate faster. In this way, heat is transferred from the hot end to the cold end of the solid bar.

68

67

915436_ch02_050-079.indd 67

915436_ch02_050-079.indd 68

9/10/09 08:20:51

9/10/09 08:20:51

Cambridge Physics IGCSE Revision Guide

Worried about covering the entire syllabus? Use the grids on the Teacher’s CD-ROMs to map each area of the syllabus to specific pages in the Student Book, to ensure nothing is missed.

Biology

Practicals and worksheets to support your lessons

PRACTICAL

Name:

Handling experimental observations and data: estimating the size of a population You need: ■

plain paper

■

pen or pencil

■

bag or small box

Method: You are provided with a bag with some pieces of paper in it� The pieces of paper represent animals in a population, and the bag is the environment in which they live� The investigation looks at a ‘capture-recapture’ technique for estimating their population size� 1 Remove between 15 and 20 ‘animals’ from the habitat (the exact number does not matter) and record this number in the table�

The Teacher’s Resource Kits are loaded with useful practicals and worksheets in print and digital form that are linked to lessons in the Student Books. Plus all the worksheets are fully customisable so you can tweak them however you please, to ensure effective teaching.

2 Mark all the pieces of paper with a small number 1 and put them back in the bag� Shake for 1 minute to mix up the ‘animals’�

Instructions take a step-bystep approach, minimising the potential for confusion

3 Remove 15–20 ‘animals’ from the bag and write down this number in the table� 4 Count how many of this second sample have got a number 1 written on them (remember to look on both sides)� 5 Estimate the size of the population using this formula: No� in first sample 3 no� in second sample ________________________________________ No� in second sample marked with a 1

6 Repeat steps 1–5 a further 4 times but mark the captured ‘animals’ in the second step with a 2 the second time, a 3 the third time, a 4 the fourth time and a 5 the fifth time� Ignore any other numbers from the earlier samples� 7 Display all the readings in the form of a table� Work out a mean value for the estimate of the population using your five sets of results� Record the mean value� 8 Tip out all of the ‘animals’ and count the actual population size� Record this value� 9 Present your results in a bar chart that shows all five of the estimates of the population and the actual value clearly�

Practicals help students apply their learning and connect it to real-world situations

10 Calculate the percentage error in your estimates compared with the actual value�

© OUP: this may be reproduced for class use solely for the purchaser’s institute

913879 COMPLETE BIOL IGCSE TG.indd 49

49

10/29/10 1:38:17 PM

Complete Biology for Cambridge IGCSE Teacher’s Resource Kit

Test it out free for thirty days Please complete in block capitals

Tick to place a firm order Tick to evaluate free for 30 days Price I/C * Qty

Title Student Books

ISBN

Complete Biology for Cambridge IGCSE

978 019 913876 0 £20.00

Complete Chemistry for Cambridge IGCSE

978 019913878 4

Complete Physics for Cambridge IGCSE

978 019 913877 7 £20.00

£20.00

School name: Address:

Complete Biology Teacher’s Kit

978 019 913879 1 £45.00

Complete Chemistry Teacher’s Kit

978 019 913881 4 £45.00

Complete Physics Teacher’s Kit

978 019 913880 7 £45.00 Country:

Revision Guides 978 019 915265 0 £11.50

Email address:†

Cambridge Chemistry IGCSE Revision Guide 978 019 915266 7 £11.50 Cambridge Physics IGCSE Revision Guide

978 019 915436 4 £11.50

* Inspection copies We send inspection copies free of

Subtotal

charge anywhere in the world. After 30 days, you can pay **P&P for the book and keep it, or return it to us at your own cost (free return postage for UK schools).

** Postage and packing is £3.85 for UK schools. Overseas schools should add 10% of the total cost of the order after discount for postage and packing up to £1,000 (minimum charge £4.25). For orders over £1,000, please contact us for details. # Discounts 10% on orders of £350+, 12.5% on orders of £750+, 15% on orders of £1,000+, 17.5% on orders of £2,000+ and 20% on orders of £2,500+.

#

Less discount (if applicable)

† By giving us your email address you are agreeing to us sending you emails about relevant OUP products and offers. Your email address will not be sold or passed onto third parties outside OUP.

Grand total

Visit us online to find your local Education Consultant www.oxfordsecondary.co.uk/igcse

tel +44 1536 452620 email [email protected] fax +44 1865 313472 web www.oxfordsecondary.co.uk/igcse

K37670

Cambridge Biology IGCSE Revision Guide

1

Name: Position:

Teacher’s Resource Kits



Total