Biology

Science

Term-I

Class-IX B.S. Tomar M.Sc., Ph.D.

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Publications Pvt. Ltd.

Syllabus Class - IX Course Structure First Term

Marks: 90

Units

Marks

I. Food

13

II. Matter - Its nature and behaviour

29

III. Organisation in the living world

18

IV. Motion, force and work

30

Total

Theme: Food

90

(10 Periods)

Unit: Food Plant and animal breeding and selection for quality improvement and management; use of fertilizers, manures;- protection from pests and diseases; organic farming.

Theme: Materials

(22 Periods)

Unit: Matter - 'Nature and behaviour Definition of matter; solid, liquid and gas; characteristics - shape, volume, density; change of state-melting (absorption of heat), freezing, evaporation (Cooling by evaporation), condensation, sublimation.

Nature of matter: Elements, compounds and mixtures. Heterogeneous and homogenous mixtures, colloids and suspensions.

Theme: The World of The Living

(22 Periods)

Unit: Organization in the living world Cell- Basic Unit of life: Cell as a basic unit of life; prokaryotic and eukaryotic cells, multicellular organisms; cell membrane and cell wall, cell organelles; chloroplast, mitochondria, vacuoles, endoplasmic reticulum, golgi apparatus; nucleus, chromosomes - basic structure, number. Tissues, Organs, Organ System, Organism. Structure and functions of animal and plant tissues (four types in animals; meristematic and permanent tissues in plants).

Theme: Moving Things, People and Ideas

(36 Periods)

Unit: Motion, force and work Motion: Distance and displacement, velocity; uniform and non-uniform motion along a straight line; acceleration, distance-time and velocity-time graphs for uniform motion and uniformly accelerated motion, equations of motion by graphical method; elementary idea of uniform circular motion. Force and Newton's laws: Force and motion, Newton's laws of motion, inertia of a body, inertia and mass, momentum, force and acceleration. Elementary idea of conservation of momentum, action and reaction forces.

Gravitation: Gravitation; universal law of gravitation, force of gravitation of the earth (gravity), acceleration due to gravity; mass and weight; free fall.

Continuous and Comprehensive Evaluation Formative Assessment •

Formative assessment is atool used by the teacher to continuously monitor student progress in anon-threatening supportive environment.

•

It involves regular descriptive feedback, achance for the student to reflect on the performance, take advice and improve upon it.

•

It involves students being an essential part of assessment from designing criteria to assessing self or peers.

•

If used effectively, it can improve performance tremendously while raising the self esteem of the child and reducing the workload of the teacher.

Summative Assessment • • •

Summative assessment is carried out at the end of a course of learning. It measures or 'sums-up' how much a student has learned from the course. It is usually a graded test, Le., it is marked according to a scale or set of grades.

Grading System Scholastic A

Scholastic B Grade Point

Grade

Exceptional

10.0

A+

A2

Excellent

9.0

A

71-80

B1

Very Good

8.0

B+

61-70

B2

Good

7.0

B

51-60

C1

Fair

6.0

C

41-50

C2

Average

5.0

33-40

0

Below Average

4.0

21-32

E1

Need to Improve

00-20

E2

Unsatisfactory

Marks Range

Grade

91-100

A1

81-90

Attributes

Promo1j'on is based on the day-to-day work of the students throughout the year and also on the performance in the terminal exami a ·on.

*Firs e ~SeGofld

term

-FA1 (10%) + FA2 (10%) + SA1 (30%)

Formative Assessment (FA) 1+2+3+4

=40%

-FA3 (10%) + FA4 (10910) + SA2 (30%)

Summative Assessment (SA) 1+2

=60%

The system being implemented will have the following advantages: •

It will minimise misclassification of students on the basis of marks.

•

It will eliminate unhealthy cut-throat competition among high achievers.

•

It will reduce societal pressure and will provide the learner with more flexibility. I

will lead to afocus towards a better learning environment.

Chapter: One

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(UJ mJ ~~ ©~ ~J~~ Introduction There are over 1.7 million kinds of organisms. They all show an enormous degree of diversity of form and size. Yet they have an underlying unity in their basic structure and process. All living structures we see around us are essentially made up of numerous compartments (microscopic units) called cell. Robert Hooke (1665) is credited with the discovery of cell. When Hooke made his chance observation through a -self-designed microscope, he observed a honeycomb-like pattern in a very thin slice of cork (Fig. 1.2). This honeycomb-like structure consisted of a thick wall enclosing box-like compartments. Hooke called these boxes, cells. Actually, cell is a Latin word for 'a small room'. This may seem an insignificant incident, but it held a lot of importance in the history of science. This was the very first time that someone had observed that living things appear to consist of such separate units. The use of the word 'cell' to describe the unit is prevalent till this day in biology.

Fig.11 Robert Hooke's rricroscope

Let us perform an activity to find out cells.

8ctivig1 • Take a small piece from an onion. • Use a forcep to separate a peel from its inner layers (concave side). • Put this inner layer immediately in a watch-glass containing water. This will prevent the peel from getting folded or dry.

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Fig. 1.2 Slice of cork showing cells

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,,,rporaf'/ mou, I a onion

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• Now, take a glass slide, put a drop of clean water on it and transfer the small piece of onion peel from the watch-glass on to the slide. Make sure that the peel is perfectly flat on the slide. • For this, you may need a thin camel hair paintbrush. • Put a drop of iodine solution on the piece of onion peel. • Gently place the cover-slip onto the slide using a mounted needle to avoid air bubbles. • This is how you prepare a temporary mount of onion peel. For observation place the slide onto the stage of the microscope. • Carefully observe the slide under microscope using the low power and high power of a compound microscope. The Fundamental Unit of Life

5

MICROSCOPE

Eyepiece --.;#'f!/:""t

: ; : . - - - - Tube Coarse adjustment Fine - - - " ' I ' adjustment

Objective lens _ _ _ (high power) 7...~---

Objective lens (low power)

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Stage height -----.;~ adjustment

Cells are very small in size and cannot be seen by the naked eye. For observing a minute cell one needs a microscope. Leeuwenhoek prepared. a light microscope which is comparable to today's compound microscope. The object (specimen) on a glass slide is kept on a stage, bearing a central hole under an objective lens. Light is reflected through the specimen with the help of a mirror and a condenser from below the stage. Through the eye piece one can see the magnified image of an object. Eye piece is located at the top. Focussing is usually done by the adjustors (coarse and fine) fitted in the microscope. Eye piece and objectives of high and low powers are available.

Fig. 1.4 Compound microscope and its parts

Cell wall I::!::=i!-- Cytopl asm

Nucleus Vacuole

Fig. 1.5 Cellular structures of onion peel

What do you observe when you look through the lens? Can you draw the structures that you are able to see through the microscope in your observation sheet? Does it look like the Fig. 1.5. When you try preparing temporary mounts of peel of onions of different sizes, you will find that all contain similar small struc;tures. These small structures which you see in an onion peel are the basic building units.called cells. ot only onions, but all organisms which you see around are made up of cells.

Discovery of Cell The term 'cell' was used by Robert Hooke in 1665. He observed cells in a piece of cork under a primitive microscope. In 1674, Anton von Leeuwenhoek discovered free cells like bacteria, protozoa, red blood cells and sperm with the help of improved microscope. Robert Brown in 1831 discovered the nucleus in the cells. In 1839, Johannes Purkinje named the fluid content of the cell as protoplasm. In 1892, O. Hertwig proposed that cell is a mass of 'protoplasm' . • Cell is the structuml and functional unit of life.

• A cell arises from a pre-existing cell.

6

Cell Theory . All plants and animals are composed of cells and that the cell is the basic unit of life, ,vas presented by two biologists-Matthias Jacob Schleiden (German Botanist) and T. Schwann (German Zoologist), in 1839. In 1855, R. Virchow further expanded the cell theory as, "Omnis cellulae a cellula", i.e., all cells arise from pre-existing cells. Soon thereafter in 1866, Haeckel, established that nucleus stores and transmits hereditary traits. In 1880, Fleming had shown that cells ensure continuity between one generation and another by The Fundamental Unit of Life

the mechanism of mitosis. Waldeyer in 1890 described the precise division of the chromosomes. Thus, the modern version ofthe cell theory is as follows: (i) All living organisms are composed of cells and their products. (ii) Cell is the structural and functional unit of life. (iii) All cells arise from pre-existing cells. (iv) The smallest unit of life is the cell, i.e., every organism starts its life as a single cell. With the discovery of electron microscope in 1940, it was possible to observe and understand the complex structure of the cell and its various organelles. The first electron microscope was designed by Knoll and Ruska in 1932.

Fig. 1.6 Electron microscope

Unicellular and Multicellular Organisms We cannot imagine an organism that is not formed of a cell. Organisms may be made up of one or more cells. If the organisms are made up ofa single cell, they are called unicellular organisms (uni-single), e.g., Amoeba, Chlamydomonas, Paramecium and bacteria. On the other hand, if organisms are made up of many cells, they are called multicellular organisms (multi-many). The multicellular organisms may be made up of few cells (e.g., some algal and fungal forms) to several million cells (e.g., human being, tree, whale, etc.). In a multicellular organism certain cells become specialised to perform a specific function and thus division of labour is established among different groups of cells. The group of cells having a common origin and performing a similar but specific function constitute a tissue (e.g., muscles). Several different types of tissues may join collectively to form an organ which carries out one or more specific functions (e.g., kidney, liver, brain). Several organs are inter-related to perform a specific function and thus, constitute an organ system (e.g., digestive system, circulatory system, nervous system, etc.). The life of every multicellular organism begins as a single cell. However, the unicellular organisms, complete their entire life cycle as a single cell. In others, .an increase in the number of cells takes place in the course of life. All the cells of our body come from a single cell, zygote, which divides continuously to form our multicellular body. Thus, all cells come from pre-existing cells. The cells are not only the building blocks of our body, they are functional units of life too. Each living cell has the capacity to perform certain basic functions that are performed by all living forms. If you study Fig. 1.10, you will observe that human beings have different types of cells like sperm, blood cell, bone cell, muscles cell, nerve cell, fat cell, etc. We know that there is division of labour in multicellular organisms, e.g., human beings. It means that different parts of the human body perform different functions. The human body has a heart to pump blood, a stomach .. to digest food and so on. Likewise, in a human body, the division of labour is also seen inside a single cell. In fact, each cell has got certain specific components inside the cell, called cell organelles. Each type of cell organelle performs a special function, e.g., protein synthesis, food synthesis, clearing up the waste material from the cell, etc. Thus, all the activities of an organism are present in miniature forms in each and every cell. So, a cell is able to live and perform its function due to these organelles. These organelles together constitute the basic unit called the cell. Therefore, the cell can be called a basic unit of life and the structural unit of an organism The Fundamental Unit of Life

7

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Cell is made of a living substance called protoplasm. (proto = first, plasma = liquid). The protoplasm is made up of four elements namely carbon, hydrogen,

nitrogen and oxygen. Other elements such as phosphorous, sulphur and calcium are also present. These elements combine to form compounds like water, proteins, fats, carbohydrates and nucleic acid (DNA and RNA), etc. activi~2 • • • • • •

Try preparing temporary mounts of leaf peels, onion root zip. lOu can also take leaf of maize, mustard or tmdescantia for this purpose. Take a red-coloured tmdescantia leaf Take out a small peel fTOm the lower surface of the leaf with a quick jerk. Prepare temporary mount of this peel. Place it under the microscope and observe it. lOu will observe that each cell is filled with red-coloured cell sap.

activi~3 • Keep a drop of your blood on a glass slide with the help of a sterile needle. • Smear the blood over- the centre of a slide with the help of another slide. • Put a drop of methylene blue stain on top of the smear and cover the slide with a coverslip. • When dry, observe the slide first under low power and then under high power microscope. • Identify and draw its structure.

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Platelets

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Red blood corpuscles ~

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You will observe the blood cells in the slide as shown in Fig. 1.7. After performing the above activity you will be able to give answer to the following questions. (i) Do all cells look alike in terms of their shape and size?

(ii) Could you find differences among cells from different parts of a plant body. (iii) \'\That similarity could you find? Answers: (i) All cells of a multicellular organism are of different shapes and sizes and cells of different organisms are different. (ii) The different parts of a plant body are different in shape, size and structure. (iii) The similarities among all the cells of higher organisms are that they contain plasma membrane, a cytoplasm which contains cell organelles and a nucleus.

Prokaryotic and Eukaryotic Cells

I

(a) Prokaryotic cell

Organisms with cells in which the nuclear material is not bounded by a definite nuclear membrane are called prokaryotes, e.g., bacteria and blue-green algae. 8

The Fundamental Unit of Life

These are the most primitive cells. Nuclear material consists of a single chromosome which is in direct contact with the cytoplasm. In a prokaryotic cell, other membranebounded organelles, such as mitochondria, endoplasmic reticulum, lysosome, chloroplast, golgi bodies, etc., are also absent. However, ribosomes are present in such cells. ..-----. ~

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Protein coat~

DNA~(\~:'J",

or RNA

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DNA

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Cytoplasm

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Cytoplasm

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Plasma membrane

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Nuclear membrane

Nodoo'", Nucleoplasm

(c)

(b)

Fig. 1.8 (a) Virus. (b) Prokaryotic ceil of bacteria. (el Eukaryotic cell of animal

I

(b) Eukaryotic cell

These are advanced and complete cells in which the nucleus has a definite nuclear membrane. In eukaryotic cells, other membrane-bounded organelles, such as mitochondria, ribosome, lisosome, E.R., chloroplast, golgi body are present. Viruses do not easily fit in the definition of a cell and they are often described as 'living chemicals' or as cellular forms which are degenerated through parasitism. Virus is an infectious, sub-cellular and ultramicroscopic particle which divides only in the host cell and can be transmitted by injection and causes characteristic reactions in the host cell. Viruses lack internal organisation which is the characteristic of a cell. The viruses living within the bacteria are called bacteriophages. The cells of bacteria are different from animal and plant cells. Bacterial cells are prokaryotic cells, whereas plant and animal cells are eukaryotic. The important differences between prokaryotic cells and eukaryotic cells have been given in Table 1.1. Table 1.1 Differences between Prokaryotic and Eukaryotic cells S.No.

Feature

Prokaryotic cells

I

Eukaryotic cells

1.

Size

Generally small, 1- 10 !-Lm

Generally large, 5-100 !-LID

2.

Cell

Non-cellulosic

Cellulosic in plants only

3.

Cell organelles

Absent except ribosomes

Present, e.g., mitochondria, endoplasmic reticulum, Golgi apparatus, lysosomes, peroxisomes, plastids, etc.

4.

Nuclear membrane

Absent. Nucleoid or nuclear Present. DNA is surrounded region is not surrounded by by a nuclear membrane nuclear membrane, i.e., DNA is n' SOU1"CeS of plant nutrients are manures and fertilisers.

VK Biology IX

94

I

Macronutrients

Micronutrients

Found in plants in large quantities. Found in plants in traces. Concentration is more than 1 mg per g Concentration is less than 1 mg per g of dry weight of plant. dry weight of plant.

3.

Not toxic even if present

4.

quantity. quantity. Examples: Carbon, Hydrogen, Examples: Zinc, Manganese, Copper, Oxygen, Nitrogen, Calcium, Potassium, Chlorine, Boron, Molybdenum, etc. Phosphorus, Magnesium, Sulphur, Iron.

In

excess Toxic if present in more than required

Use of Manures and Fertilisers

Manures and fertilisers increase the fertility of the soil of crop fields. They also remove the deficiency of plant nutrients of the soil. They are used to increase the crop production. Improvement in Food Resources

1. Manures

Manures are natural fertilisers which are being used since ancient days. ~anures add small quantities of nutrients and large quantities of organic matter m the soil and make the soil soft for the better growth of root system and in turn plant growth. Capacity of holding water in the soil, etc., also increases. The microorganisms of the soil, beneficial to the soil and crop also get food. Manures are required in bulk quantities in comparison to chemical fertilisers. Large quantities of organic matter in clayey soils help in drainage of water and also avoid water logging. Types of Manures Manures are of three types: (I) Farm Yard Manure (2) Compost (3) Green Manure

• Manw-es are used in

bulk before sowing seeds (croP).

(1) Farm yard manure (FYM): It is the decomposed matter of cattle dung

(faecal matter), urine and litter, i.e., bedding material used in winter months at night under cattles. It also includes the leftover fodder in their manures. These materials are dumped daily in especially constructed pit away from the cattle shed. Action of microbes (e.g., bacteria, fungi, etc.) developed in this excreta, converts (decompose) it into manure, which is ready to spread in the crop fields. Farmyard manure is used in field before the sowing of crop, i.e., in October and in May/June in northern India. FYM is rich in potassium, phosphorus and nitrogen. It contains about 0.5 per cent potassium oxide, 0.15 per cent phosphorus pentoxide and 0.5 per cent nitrogen. (2) Compost: It includes farm and town refuge (e.g., vegetable matter, animal refuge such as excreta of domestic animals and stray animals, human faecal matter (sewage, etc.) stored in open fields beyond the limits of town (human population). Like FYM, it is also a biological process in which aerobic and anaerobic microorganisms decompose the town and city garbage and sewage waste into compost. Decomposition occurs between 3 to 6 months. Compost from town refuge contains about 1.4 per cent nitrogen, 1.0 percent phosphorus pentoxide and 1.4 per cent potassium oxide. While farm compost contains 0.5% nitrogen, 0.15% P205 and 0.5% K20. Method of preparing compost: For making compost, a trench or pit of 4 to 5 m long, 1.5 to 1.8 m broad and I to 1.8 m deep is dug. In it a layer of mixed refuse is spread. It should be about 30 cm in thickness. This is moistened with water and cattle dung or water and earth. Over it again mixed refuse is added which rises to a height of 45 to 60 cm above the ground level. ow the top is covered with a thin layer of earth. This is kept as such for 3 months, then it is taken out of the trench and formed into a conical heap. Again moisten it if necessary and cover it with earth. Leave it again for one or two months. Now the compost is ready to use in the fields. Town sewage is also recycled mechanically in activated sludge system in which solid wastes settle down at the bottom of the plant. It is called sludge. The upper clear water (sewage water) is being used in irrigation purposes and the organic waste is dried and used as manure. (3) Green manure: In green manure, generally leguminous as well as nonleguminous herbaceous plant seeds are sown in summers before the rainy season for about 6 to 8 weeks. These are sunhemp (Crotalaria juneea) , berseem (Egyptian clover-Trifolium alexandrium) , sesbania or dhaincha (Sesbania aeuleata) and guar or cluster bean (Cyamopsis tetragonoloba), cowpea (lobia), lentils (massur) , etc. These plants near the onset of monsoon are ploughed and buried in the field at a tender stage, i.e., at flowering stage. In the rainy rovement in Food Resources

• Composting is a biological process in which both aeTobie and anaerobic rmcroorganzsms decompose organic

"//Illtler in 3-6 months.

95

VK Biology IX

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season these plants get decomposed with the help of decomposers. Then the new cereal crop is sown. Green manure adds nitrogen and organic matter in the soil. This adds to the fertility of the soil. It forms a protective soil cover and thus checks soil erosion and leaching. It increases the crop yield by 30 to 50 per cent. Green manure is used in this region by some large farmers. l:.artll\mrms in the soil especially after rains turn down the soil. They feed on soil containing organic matter and their casting is also rich in organic matter. They make the soil porous and increase the soil fertility. This type of composting is called \