Class 8 Science 1 to 9 Chapters Solutions (Part A)

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CLASS-8

SUBJECT-SCIENCE

CH- 1 To 9

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CH-1 Crop Production and Management

Exercise : Solutions of Questions on Page Number : 13

Q1 :

Select the correct word from the following list and fill in the blanks.

float, water, crop, nutrients, preparation

(a) The same kind of plants grown and cultivated on a large scale at a place is called _________.

(b) The first step before growing crops is ________ of the soil.

(d) For growing a crop, sufficient sunlight and _________ and _________ from the soil are essential.

Answer :

(a) The same kind of plants grown and cultivated on a large scale at a place is called crop .

(b) The first step before growing crops is preparation of the soil.

(d) For growing a crop, sufficient sunlight and water and nutrients from the soil are essential.

Q2 :

Match items in column A with those in column B.

A B

(i) Kharif crops (a) Food for cattle

(ii) Rabi crops (b) Urea and super phosphate

(iii) Chemical fertilisers (c) Animal excreta, cow dung, urine and plant waste

(iv) Organic manure (d) Wheat, gram, pea

(e) Paddy and maize

Answer :

A B

(i) Kharif crops (e) Paddy and maize

(ii) Rabi crops (d) Wheat, gram, pea

(iii) Chemical fertilisers (b) Urea and super phosphate

(iv) Organic manure (c) Animal excreta, cow dung, urine and plant waste

Q3 :

Give two examples of each.

(a) Kharif crop

(b) Rabi crop

Answer :

(a) Kharif crop → Paddy, maize

(b) Rabi crop → Wheat, gram

Q4 :

Write a paragraph in your own words on each of the following.

(a) Preparation of soil (b) Sowing

Answer :

(a) Preparation of soil:

It is the first method to be followed before growing a crop. This method is usually employed for loosening the soil to allow the root to

penetrate deep into it. The loosening of the soil helps in the growth of several soil microbes, earthworms etc., which enrich the soil

with humus and other essential nutrients. Plants require nutrients for their proper growth and functioning. The process of loosening

is called tilling or ploughing the soil. Tilling of soil brings the nutrient-rich soil to the top. This helps the plants to utilize the nutrients

for their growth.

(b)Sowing:

Sowing is another important step in crop production. It is the process of placing the seed in or on the soil for future growth. The

seeds that are selected for growing should be of good quality. This will improve the net yield of the crop. Sowing is usually done with

the help of either a traditional tool or a seed drill. The traditional tool is shaped like a funnel. It was used earlier for sowing seeds.

Nowadays, seed drills that make the use of tractors are used for sowing seeds. This tool disperses seeds uniformly and sows seeds

at proper depth. Sowing by this method saves time and also protects the seeds from birds.

(c)Weeding:

Undesirable plants that grow along with the crop are known as weeds. Weeding is the process of removing these

weeds.Xanthium, Parthenium, etc. are some common weeds. Weeds compete with the crop for nutrients, light, and space. As a

result, crop plants get lesser nutrients, light, and space for their development. This in turn, reduces their productivity. Thus, various

weeding methods are employed.

Some important weeding methods are:

(i) Weeds can be controlled using weedicides. It is a chemical, which is sprayed in the fields to kill all available weeds. Weedicides

are not harmful to crops.

(ii) Tilling before sowing of crops also helps in removing weeds. Tilling uproots the weeds. The best time for removal of weeds is

before they produce flowers and seeds.

(iii) The manual method of removing weeds is with the help of a khurpi. It involves regular uprooting or cutting of weeds close to the

ground.

(d)Threshing:

Threshing is the process of separating grains or seeds from chaff. It is done after harvesting the crop. It is usually carried out with

the help of a machine known as 'Combine'. This machine is a combined harvester and thresher. It harvests plants as well as cleans

grains.

Q5 :

Explain how fertilisers are different from manure.

Answer :

Differences between fertilisers and manure:

Fertiliser Manure

Fertilisers are commercially available plant

nutrients.

Manure is a natural substance prepared

by the decomposition of animal excreta

and plant wastes.

They can be organic or inorganic in nature.

Manure is known to have a large

quantity of organic materials and very

little amount of plant nutrients.

They ensure healthy growth and development

of plants by providing them with nitrogen,

phosphorus, potassium, etc.

They help in enriching the soil with

organic matter and nutrients.

The addition of fertilisers to the soil requires

special guidelines such as dose time, post

addition precautions, etc., to be followed.

The addition of manure does not require

any special guidelines.

A fertiliser does not provide any humus to the

soil.

Manure provides humus to the soil and

increases soil fertility.

Its excessive use causes water pollution. It

cannot replenish organic matter of soil.

It protects the environment and helps in

recycling farm waste.

Q6 :

What is irrigation? Describe two methods of irrigation which conserve water.

Answer :

Irrigation is the process by which water is supplied to crops at different intervals. The time and frequency of irrigation varies

according to different seasons, crops, and soil types. There are various sources of irrigation such as wells, canals, rivers, dams,

ponds, and lakes.

Two methods of irrigation which help in conservation of water are:

a) Sprinkler system:

This system is more useful on uneven land, having fewer water supplies. In this method, water is supplied using pipes to one or

more central locations within the field. When water is allowed to flow under high pressure with the help of a pump, it gets sprinkled

on the crops.

b)Drip system:

In this system, water is delivered at or near the roots of plants, drop by drop. This is the most efficient method of irrigation as there is

no wastage of water at all. This method is important in areas where water availability is poor.

Q7 :

If wheat is sown in the kharif season, what would happen? Discuss.

Answer :

If wheat is sown in the kharif season (from June to October), then the whole crop might get destroyed because of many factors such

as lack of optimum temperature, adaptability, availability of pests, etc. Kharif season includes the rainy season, which is not

favourable for the growth of wheat crop. Therefore, wheat crop should not be sown during this season.

Q8 :

Explain how soil gets affected by the continuous plantation of crops in a field.

Answer :

Continuous plantation of crops in a field makes the soil poor in certain nutrients such as nitrogen, phosphorus, potassium, etc.

Plants require nutrients for their proper growth and functioning. When a farmer continues to grow crops one after the other, then all

nutrients available in the soil reduce and the crop yield decreases automatically.

Q9 :

What are weeds? How can we control them?

Answer :

Undesirable plants that grow along with crop plants are known as weeds. Xanthium, Parthenium, etc. are some common weeds.

Weeds compete with the crop for nutrients, light, and space. As a result, crop plants get lesser nutrients, light, and space for their

development. This in turn, reduces their productivity. Thus, various weeding methods are employed.

Some important weeding methods are:

i. Weeds can be controlled using weedicides. It is a chemical, which is sprayed in the fields to kill all available weeds. Weedicides are not

harmful to crops.

ii. Tilling before sowing of crops also helps in removing weeds. Tilling uproots the weeds. The best time for the removal of weeds is before

they produce flowers and seeds.

iii. The manual method of removing weeds is with the help of a khurpi. It involves regular uprooting or cutting of weeds close to the ground.

Q10 :

Arrange the following boxes in proper order to make a flow chart of sugarcane crop production.

CH-2 Microorganism: Friend And Foe

Exercise : Solutions of Questions on Page Number : 29

Q1 :

Fill in the blanks:

(a) Microorganisms can be seen with the help of a _________.

(b) Blue green algae fix _________ directly from air to enhance fertility of soil.

(d) Cholera is caused by _________.

Answer :

(a) Microorganisms can be seen with the help of a _microscope _.

(b) Blue green algae fix __ nitrogen_ directly from air to enhance fertility of soil.

(d) Cholera is caused by _ bacteria_.

Q2 :

Tick the correct answer:

(a) Yeast is used in the production of

(i) sugar

(ii) alcohol

(iii) hydrochloric acid

(iv) oxygen

(b) The following is an antibiotic

(i) Sodium bicarbonate

(ii) Streptomycin

(iii) Alcohol

(iv) Yeast

(i) female Anopheles mosquito

(ii) cockroach

(iii) housefly

(iv) butterfly

(d) The most common carrier of communicable diseases is

(i) ant

(ii) housefly

(iii) dragonfly

(iv) spider

(e) The bread or idli dough rises because of

(i) heat

(ii) grinding

(iii) growth of yeast cells

(iv) kneading

(f) The process of conversion of sugar into alcohol is called

(i) nitrogen fixation

(ii) moulding

(iii) fermentation

(iv) infection

Answer :

(a) Yeast is used in the production of

(i) sugar

(ii) alcohol

(iii) hydrochloric acid

(iv) oxygen

(b) The following is an antibiotic

(i) sodium bicarbonate

(ii) streptomycin

(iii) alcohol

(iv) yeast

(i) female Anopheles mosquito

(ii) cockroach

(iii) housefly

(iv) butterfly

(d)The most common carrier of communicable diseases is

(i) ant

(ii) housefly

(iii) dragonfly

(iv) spider

(e)The bread or idli dough rises because of

(i) heat

(ii) grinding

(iii) growth of yeast cells

(iv) kneading

(f) The process of conversion of sugar into alcohol is called

(i) nitrogen fixation

(ii) moulding

(iii) fermentation

(iv) infection

Q3 :

Match the organisms in Column I with their action in Column II.

Column I Column II

(i) Bacteria (a) Fixing nitrogen

(ii) Rhizobium (b) Setting of curd

(iii) Lactobacillus (c) Baking of bread

(iv) Yeast (d) Causing malaria

(v) A protozoan (e) Causing cholera

(vi) A virus (f) Causing AIDS

(g) Producing antibody

Answer :

Column I Column II

(i) Bacteria (e) Causing cholera

(ii) Rhizobium. (a) Fixing nitrogen

(iii) Lactobacillus (b) Setting of curd

(iv) Yeast (c) Baking of bread

(v) A protozoan (d) Causing malaria

(vi) A virus (f) Causing AIDS

Q4 :

Can microorganisms be seen with the naked eye? If not, how can they be seen?

Answer :

Micro-organisms are too small to be seen through naked eyes. They can be seen with the help of a magnifying glass or microscope.

For example, fungus that grows on bread is so small that it can be seen only with the help of a magnifying glass or microscope.

Q5 :

What are the major groups of microorganisms?

Answer :

There are five major groups of micro-organisms:

(i) Bacteria - They are single celled disease-causing micro-organisms. They can be spiral or rod- shaped.

(ii) Fungi - They are mostly multicellular disease-causing microbes. Bread moulds are common examples of fungi.

(iii) Protozoa - They mainly include organisms such as Amoeba, Plasmodium,etc. They can be unicellular or multicellular.

(iv) Virus -Viruses are disease-causing microbes that reproduce only inside the host organism.

(v) Algae - They include multicellular, photosynthetic organisms such as Spirogyra, Chlamydomonas, etc.

Q6 :

Name the microorganisms which can fix atmospheric nitrogen in the soil.

Answer :

Bacteria such as Rhizobium and certain blue-green algae present in the soil can fix atmospheric nitrogen and convert it into usable

nitrogenous compounds. These nitrogenous compounds can be easily utilized by plants for the synthesis of plant proteins and other

compounds.

Q7 :

Write 10 lines on the usefulness of microorganisms in our lives.

Answer :

Micro-organisms are too small to be seen through naked eyes. However, they are vital to plants and the environment.

Importance of micro-organisms:

They are used in winemaking, baking, pickling, and other food making processes.

Alcoholic fermentation by yeast is widely used in the preparation of wine and bread. A bacterium Lactobacillus, promotes the

formation of curd.

Microbes are used to reduce pollution. For example, decomposers such as bacteria and fungi break down dead bodies and excreta

to form inorganic compounds, which can be absorbed by plants.

They are used to increase the soil fertility by fixing the atmospheric nitrogen with the help of bacterium Rhizobium and some other

blue-green algae.

Microbes also play an important role in the preparation of medicines. Antibiotics are chemicals produced by micro-organisms to kill

bacteria. Streptomycin, for example, is an antibiotic.

Certain microbes are also used in the biological treatment of sewage and industrial effluents.

Q8 :

Write a short paragraph on the harms caused by microorganisms.

Answer :

Harmful effects of micro-organisms:

Micro-organisms cause diseases in animals. For example, in humans, bacteria cause diseases such as tuberculosis, cholera,

typhoid, etc. In cattle, the foot and mouth disease is caused by a virus. Also, several microbes cause diseases in plants. For

example, the productivity of wheat, orange, apple, etc. is reduced due to microbial diseases in plants. Certain microbes, on entering

into our body, produce toxic substances. This leads to food poisoning. Some micro-organisms such as fungus spoil our food. For

example, bread when left unused under moist conditions gets spoilt by fungus, producing a white cotton-like growth on the bread.

Q9 :

What are antibiotics? What precautions must be taken while taking antibiotics?

Answer :

Antibioticsare medicines produced by certain micro-organisms to kill other disease-causing micro-organisms. These medicines are

commonly obtained from bacteria and fungi. Streptomycin, tetracycline, penicillin, etc. are common antibiotics.

Precautions to be taken while using antibiotics:

(i) Antibiotics should be taken under the supervision of a well qualified doctor.

(ii) Course (intake) of antibiotics should be completed as per the prescription given by the doctor.

(iii) Antibiotics should be taken in the right amount and at the right time. A wrong dose of antibiotics makes the drug ineffective. Also,

excessive consumption of drugs may kill the useful bacteria present in our body.

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CH-3 Synthetic Fibers and Plastics

Exercise : Solutions of Questions on Page Number : 41

Q1 :

Explain why some fibres are called synthetic.

Answer :

There are some fibres that are prepared by man by using chemicals. These are called synthetic fibres. These are made of small

units that join together to form long chains. Examples of synthetic fibres are rayon, nylon, polyester, acrylic, etc.

Q2 :

Mark ( ) the correct answer.

Rayon is different from synthetic fibres because

(a) it has a silk-like appearance.

(b) it is obtained from wood pulp.

Answer :

Rayon is different from synthetic fibres because

(a) it has a silk-like appearance.

(b) it is obtained from wood pulp. (correct)

Q3 :

Fill in the blanks with appropriate words.

(a) Synthetic fibres are also called _______ __or _______ __fibres.

(b) Synthetic fibres are synthesised from raw materials called _______ __.

Answer :

(a) Synthetic fibres are also called artificial or man-made fibres.

(b) Synthetic fibres are synthesised from raw materials called petrochemicals.

Q4 :Give examples which indicate that nylon fibres are very strong.

Answer :

Nylon fibres are very strong. It is used for making ropes used for climbing rocks and for making parachutes. Their usage shows that

nylon fibres have high tensile strength.

Q5 :

Explain why plastic containers are favoured for storing food.

Answer :

The characteristics that make plastics favourable for storing food items are:

(i) Light weight

(ii) Lower price

(iii) Good strength

(iv) Easy handling

Q6 :

Explain the difference between thermoplastic and thermosetting plastics.

Answer :

Thermosetting Plastic		there are two types of plastics: Thermosetting plastics and Thermoplastics.	Thermosetting plastic cannot be bent easily. It may break when forced to bend.	Thermosettingplastic cannot be softened by heating. Thus, it cannot be reshaped once moulded.
Thermoplastic	Thermoplastic can be bent easily.	Thermoplastic can be softened easily by heating. Thus, it can be reshaped.

Q7 :

Explain why the following are made of thermosetting plastics.

(a) Saucepan handles

(b) Electric plugs/switches/plug boards

Answer :

(a) Saucepan handles are made of thermosetting plastics because these plastics do not get softened on heating. Also,

thermosetting plastics such as bakelite are poor conductors of heat.

(b) Thermosetting plastics such as bakelite are poor conductors of heat and electricity. Therefore, they are used for making electric

plugs, switches, plug boards, etc.

Q8 :

Categorize the materials of the following products into 'can be recycled' and 'cannot be recycled'.

Telephone instruments, plastic toys, cooker handles, carry bags, ball point pens, plastic bowls, plastic covering on

electrical wires, plastic chairs, electrical switches.

Answer :

Cannot be recycled Can be recycled

Telephone instruments Plastic toys

Cooker handles Plastic chairs

Electrical switches Carry bags

Plastic covering on electrical wires

Ball point pens

Plastic bowls

Q9 :

Rana wants to buy shirts for summer. Should he buy cotton shirts or shirts made from synthetic material? Advise Rana,

giving your reason.

Answer :

Rana should buy shirts made from cotton. This is because cotton is a good absorber of water. It can soak the sweat coming out of

our body and expose it to the environment. Thus, it helps in evaporating the liquid (sweat), thereby cooling our body.

Q10 :

Give examples to show that plastics are non-corrosive in nature.

Answer :

Plastics are not corroded even if they come in contact with strong chemicals. This is because of their non-reactive nature with most

materials. For example, the cleansing chemicals that we use at home are stored in plastic bottles, instead of metal containers.

Q11 :

Should the handle and bristles of a tooth brush be made of the same material? Explain your answer.

Answer :

No. The handle and bristles of a tooth brush should be made of different materials. The handle of a toothbrush should be hard and

strong, while the bristles should be soft and flexible.

Q12 :

'Avoid plastics as far as possible'. Comment on this advice.

Answer :

Plastics are non-biodegradable. Once introduced into the environment, they take several years to decompose. Plastics add to the

environmental pollution. They cannot be burnt as when burnt, they release poisonous gases. Plastic bags thrown in the garbage

dump are swallowed by animals like cows. These plastic bags choke their respiratory system and can even prove fatal. Therefore,

we should avoid plastics as far as possible.

Q13 :

Match the terms of column A correctly with the phrases given in column B.

A B

(i) Polyester (a) Prepared by using wood pulp

(ii) Teflon (b) Used for making parachutes and stockings

(iii) Rayon (c) Used to make non-stick cookware

(iv) Nylon (d) Fabrics do not wrinkle easily

Answer :

A B

(i) Polyester (d) Fabrics do not wrinkle easily

(ii) Teflon (c) Used to make non-stick cookware

(iii) Rayon (a) Prepared by using wood pulp

(iv) Nylon (b) Used for making parachutes and stockings

Q14 :

'Manufacturing synthetic fibres is actually helping conservation of forests'. Comment.

Answer :

Raw materials for natural fibres are mainly derived from plants and this means cutting a lot of trees. This leads to deforestation. But

raw materials of synthetic materials are mainly petrochemicals. Hence, manufacturing synthetic fibres helps in the conservation of

forests.

Q15 :Describe an activity to show that thermoplastic is a poor conductor of electricity.

Answer :

We will design a circuit to see that thermoplastics are poor conductors of electricity. We need a bulb, some wires, a battery, a piece

of metal, and a plastic pipe. Set up the circuit first with the metal and then with the plastic pipe (as shown in the figure). After you

switch on the current, you will observe that the bulb glows in the former case. In the latter case, the bulb does not glow. Hence, a

plastic pipe (which is a thermoplastic) is shown to be a poor conductor of electricity

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CH-4 Materials : Metals and Non-Metals

Exercise : Solutions of Questions on Page Number : 53

Q1 :

Which of the following can be beaten into thin sheets?

(a) Zinc (b) Phosphorus (c) Sulphur (d) Oxygen

Answer :

(a) Zinc

Q2 :

Which of the following statements is correct?

(a) All metals are ductile.

(b) All non-metals are ductile.

(d) Some non-metals are ductile.

Answer :

However, mercury metal- a liquid at room temperature - cannot be drawn into wires and is not ductile.

Q3 :

Fill in the blanks:

(a) Phosphorus is a very _________non-metal.

(b) Metals are ________ conductors of heat and _________.

(d) Metals react with acids to produce _________gas.

Answer :

(a) Phosphorus is a very reactive non-metal.

(b) Metals are good conductors of heat and electricity.

(d) Metals react with acids to produce hydrogengas.

Q4 :

Mark 'T' if the statement is true and 'F' if it is false.

(a) Generally, non-metals react with acids. ( )

(b) Sodium is a very reactive metal. ( )

(d) Coal can be drawn into wires. ( )

Answer :

(i) Generally, non-metals react with acids. (F)

(ii) Sodium is a very reactive metal. (T)

(iii) Copper displaces zinc from zinc sulphate solution. (F)

(iv) Coal can be drawn into wires. (F)

Q5 :

Some properties are listed in the following Table. Distinguish between metals and non-metals on the basis of these

properties.

Properties Metals Non-metals

1. Appearance

2. Hardness

3. Malleability

4. Ductility

5. Heat Conduction

6. Conduction of Electricity

Answer :

Properties Metals Non-metals

1. Appearance

2. Hardness

3. Malleability

4. Ductility

5. Heat conduction

6. Conduction of

electricity

Lustrous

Hard

Can be beaten into thin

sheets

Can be drawn into wires

Good conductors of heat

Good conductors of

electricity

Dull

Soft

Cannot be beaten into thin

sheets

Cannot be drawn into wires

Poor conductors of heat

Poor conductors of electricity

Q6 :

Give reasons for the following.

(a) Aluminium foils are used to wrap food items.

(b) Immersion rods for heating liquids are made up of metallic substances.

(d) Sodium and potassium are stored in kerosene.

Answer :

(a) Aluminium foils are used to wrap food items because aluminium metal is malleable. Therefore, it can be beaten into thin foils.

(b) Metals are good conductors of heat and electricity. Therefore, immersion rods for heating liquids are made of metallic

substances.

(c) A metal can displace a less reactive metal from its salt in an aqueous solution. But zinc is more reactive than copper. Therefore,

copper cannot displace zinc from its salt solution.

Cu(s)+ ZnSO4 (aq) → No reaction

(d) Sodium and potassium are stored in kerosene because they are highly reactive elements. They can easily catch fire even when

in contact with air.

Q7 :

Can you store lemon pickle in an aluminium utensil? Explain.

Answer :

Lemon pickle cannot be stored in aluminium utensils because lemon pickle contains acids, which can react with aluminium (metal)

liberating hydrogen gas. This can lead to the spoiling of the pickle.

Q8 :

Match the substances given in Column A with their uses given in Column B.

A B

(i) Gold (a) Thermometers

(ii) Iron (b) Electric wire

(iii) Aluminium (c) Wrapping food

(iv) Carbon (d) Jewellery

(v) Copper (e) Machinery

(vi) Mercury (f) Fuel

Answer :

A B

(i) Gold (d) Jewellery

(ii) Iron (e) Machinery

(iii) Aluminium (c) Wrapping food

(iv) Carbon (f) Fuel

(v) Copper (b) Electric wire

(vi) Mercury (a) Thermometers

Q9 :

What happens when

(a) Dilute sulphuric acid is poured on a copper plate?

(b) Iron nails are placed in copper sulphate solution?

Write word equations of the reactions involved.

Answer :

(a) When dilute sulphuric acid is poured on a copper plate, there will be no reaction between copper and dilute sulphuric acid as

copper is less reactive and hence no products will be formed.

(b) Iron being more reactive displaces copper from copper sulphate solution. In this reaction, the blue colour of copper sulphate

fades and there is deposition of copper on the iron nail.

Q10 :

Saloni took a piece of burning charcoal and collected the gas evolved in a test tube.

(a) How will she find the nature of the gas?

(b) Write down word equations of all the reactions taking place in this process.

Answer :

(a) Add a few drops of water in the test tube containing gas. Now, cover the test tube and shake it well. After shaking, test the

solution with blue litmus and red litmus. It will turn blue litmus red. Thus, the gas is acidic in nature.

(b) Charcoal reacts with oxygen to form carbon dioxide gas.

Carbon dioxide reacts with water to form carbonic acid, which turns blue litmus paper red.

Q11 :

One day Reeta went to a jeweller's shop with her mother. Her mother gave an old gold jewellery to the goldsmith to polish.

Next day when they brought the jewellery back, they found that there was a slight loss in its weight. Can you suggest a

reason for the loss in weight?

Answer :

To polish a gold ornament, it is dipped in a liquid called aqua regia (a mixture of hydrochloric acid and nitric acid). On getting the

environment of aqua regia, the outer layer of gold dissolves and the inner shiny layer appears. The dissolving of the layer causes a

reduction in the weight of the jewellery.

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CH-5 Coal and Petroleum

Exercise : Solutions of Questions on Page Number : 62

Q1 :

What are the advantages of using CNG and LPG as fuels?

Answer :

The advantages of using compressed natural gas (CNG) and liquified petroleum gas (LPG) as fuels are:

(i) They can be burnt directly.

(ii) They can be transported easily through pipe lines.

(iii) They are clean fuels and do not give smoke when burnt.

(iv) They give a lot of heat energy when burnt.

Q2 :

Name the petroleum product used for surfacing of roads.

Answer :

Bitumen, a petroleum product, is used for surfacing roads.

Q3 :

Describe how coal is formed from dead vegetation. What is this process called?

Answer :

Millions of years ago, dense forests got buried under the soil due to natural processes like storms, floods, and earthquakes. These

got compressed as more and more soil got deposited over them. When they got buried deep in the soil, they were exposed to very

high pressure and temperature. Under these conditions, these slowly got converted into coal. This process of formation of coal from

dead vegetation is called carbonization.

Q4 :

Fill in the banks.

(a) Fossil fuels are ________, ________and _________.

(b) Process of separation of different constituents from petroleum is called _________.

Answer :

(a) Fossil fuels are coal,petroleum and natural gas.

(b) Process of separation of different constituents from petroleum is called refining.

Q5 :

Tick True/False against the following statements.

(a) Fossil fuels can be made in the laboratory. (T / F)

(b) CNG is more polluting fuel than petrol. (T / F)

(d) Coal tar is a mixture of various substances. (T / F)

(e) Kerosene is not a fossil fuel. (T / F)

Answer :

(a) Fossil fuels can be made in the laboratory. (F)

(b) CNG is more polluting fuel than petrol. (F)

(d) Coal tar is a mixture of various substances. (T)

(e) Kerosene is not a fossil fuel. (F)

Q6 :

Explain why fossil fuels are exhaustible natural resources.

Answer :

Fossil fuels require millions of years to form from the dead vegetation and animals that get buried deep inside the Earth. They

require high temperature and pressure for their formation, which cannot be provided in the laboratory. Thus, fossils are limited.

Therefore, the use of fossil fuels at this rate will lead to their exhaustion.

Q7 :

Describe characteristics and uses of coke.

Answer :

Characteristics of coke are:

(i) Tough

(ii) Porous

(iii) Black in colour

Uses of coke:

(i) In manufacture of steel.

(ii) In the extraction of metals (as a reducing agent).

Q8 :

Explain the process of formation of petroleum.

Answer :

Petroleum was formed from dead organisms that got buried in the sea millions of years ago. These dead bodies got covered with

layers of sand and clay. Lack of air, high temperature, and high pressure transformed these dead organisms into petroleum and

natural gas.

Q9 :

The following Table shows the total power shortage in India from 1991 - 1997. Show the data in the form of a graph. Plot

shortage percentage for the years on the Y-axis and the year on the X-axis.

S. No year Shortage (%)

1. 1991

2. 1992

3. 1993

4. 1994

5. 1995

6. 1996

7. 1997

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CH-6 Combustion and Flame

Exercise : Solutions of Questions on Page Number : 75

Q1 :

List conditions under which combustion can take place.

Answer :

Combustion is a process of reaction of a substance with oxygen. There are certain conditions required for combustion to take place.

They are:

(i) Presence of a fuel

(ii) Air (or oxygen)

(iii) Ignition temperature (minimum temperature at which a substance catches fire)

Q2 :

Fill in the blanks:

(a) Burning of wood and coal causes _______ __of air.

(b) A liquid fuel used in homes is ___________.

(d) Fire produced by oil cannot be controlled by ________ _.

Answer :

(a) Burning of wood and coal causes __pollution__of air.

(b) A liquid fuel used in homes is __liquefied petroleum gas (LPG)_.

(d) Fire produced by oil cannot be controlled by __water__.

Q3 :

Explain how the use of CNG in automobiles has reduced pollution in our cities.

Answer :

Combustion of fuels like petroleum causes formation of un-burnt carbon particles along with carbon monoxide gas. These harmful

pollutants enter the air and cause respiratory diseases. Compressed Natural Gas (CNG) produces these harmful products in very

less quantity. It is a comparatively cleaner fuel. Therefore, the use of CNG has reduced pollution in our cities.

Q4 :

Compare LPG and wood as fuels.

Answer :

Wood has been a traditional fuel for both domestic and industrial use. However, it produces a lot of smoke that can cause

respiratory problems. Also, wood is obtained from trees. Thus, using wood as a fuel causes deforestation. Therefore, slowly wood is

replaced by LPG, which is a liquefied form of petroleum gas. It does not give out smoke and other pollutants and is a cleaner fuel.

Again, fuel efficiency of LPG is more than that of wood. The calorific value of LPG is 55000 kJ / kg, while that of wood is between

17000 to 22000 kJ / kg. Hence, LPG is favoured over wood.

Q5 :

Give reasons.

(a) Water is not used to control fires involving electrical equipment.

(b) LPG is a better domestic fuel than wood.

Answer :

(a) Water is a good conductor of electricity. If it is used for controlling a fire involving electrical equipments, then the person dousing

the fire might get an electric shock. Also, water can damage electrical equipments.

(b) LPG is a better domestic fuel as it does not produce smoke and un-burnt carbon particles, which cause respiratory problems.

(c) A piece of paper wrapped around aluminium pipe does not catch fire easily. This is because aluminium, being a metal, is a good

conductor of heat. Therefore, heat is transferred from the paper to the metal and the paper does not attain its ignition temperature.

Q6 :

Make a labelled diagram of a candle flame.

Answer :

Q7 :

Name the unit in which the calorific value of a fuel is expressed.

Answer :

The calorific value of a fuel is expressed in kilojoules per kilogram (kJ/kg).

Q8 :

It is difficult to burn a heap of green leaves but dry leaves catch fire easily. Explain.

Answer :

Green leaves have a lot of moisture in them. This moisture does not allow them to catch fire easily. However, dry leaves have no

moisturein them. Therefore, they catch fire easily.

Q9 :

Which zone of a flame does a goldsmith use for melting gold and silver and why?

Answer :

Goldsmiths use the outermost part/zone of the flame to melt gold and silver. This is because the outermost zone of the flame

undergoes complete combustion and is the hottest part of the flame.

Q10 :

In an experiment 4.5 kg of a fuel was completely burnt. The heat produced was measured to be 180,000 kJ. Calculate the

calorific value of the fuel.

Answer :

The calorific value of fuel is the amount of heat produced by the complete combustion of 1 kg of fuel.

Now,

Heat produced by 4.5 kg of fuel = 180000 kJ

Therefore, heat produced by kJ/kg

= 40,000 kJ/kg

Hence, the calorific value of the fuel is 40,000 kJ/kg.

Q11 :

Can the process of rusting be called combustion? Discuss.

Answer :

Combustion is a chemical process in which a substance reacts with oxygenand gives out energy during the process in the form of

either heat or light or both. Rusting of iron is an exothermic process as heat is released during rusting. Hence, it is a kind of slow

combustion.

Q12 :

Abida and Ramesh were doing an experiment in which water was to be heated in a beaker. Abida kept the beaker near the

wick in the yellow part of the candle flame. Ramesh kept the beaker in the outermost part of the flame. Whose water will

get heated in a shorter time?

Answer :

The water in the Ramesh's beaker will heat up in a shorter time. This is because the outermost zone of a flame is the hottest zone,

while the yellow zone (in which Abida had kept the beaker) is less hot.

____________________________________________________________________________________________

CH-7 Conservation of Plants and Animals

Exercise : Solutions of Questions on Page Number : 86

Q1 :

Fill in the blanks:

(a) A place where animals are protected in their natural habitat is called a __ .

(b) Species found only in a particular area are known as ______.

Answer :

(a) A place where animals are protected in their natural habitat is called a sanctuary.

(b) Species found only in a particular area are known as endemic.

Q2 :

Differentiate between the following.

(a) Wildlife sanctuary and biosphere reserve

(b) Zoo and wildlife sanctuary

(d) Flora and fauna

Answer :

(a)

Wildlife sanctuary Biosphere reserve

It is an area within which animals are protected

from possible dangers such as hunting. Their

habitat is also conserved in this area.

It is a large protected area constructed

for the conservation of biodiversity.

It provides protection and suitable living

conditions to wild animals.

It helps in the conservation of various

life forms such as plants, animals, and

micro-organisms.

Pachmarhi sanctuary is a wildlife sanctuary. Pachmarhi biosphere reserve is a

popular biosphere reserve.

(b)

Zoo Wild life sanctuary

It is a facility in which

animals are kept for public

exhibition.

It is an area within which animals are protected from

possible dangers such as hunting. Their habitat is also

conserved in this area.

It is an artificial habitat. It conserves the natural habitat of animals.

(c)

Endangered species Extinct species

It is a population of species that is on the

verge of becoming extinct.

It is a population of species that no longer

exists. Hence, it is extinct.

Blue whale, tiger, leopard, etc. are examples

of endangered species.

Dodo, passenger pigeon, etc. are examples

of extinct species.

(d)

Flora Fauna

It refers to all living plants in a particular

area.

It refers to all animals living in a particular

area.

Sal, teak, mango, etc. form the flora of

Pachmarhi biosphere reserve.

Leopard, wolf, wild dog, etc. form the fauna

of Pachmarhi biosphere reserve.

Q3 :

Discuss the effects of deforestation on the following.

(a) Wild animals

(b) Environment

(d) Cities (Urban areas)

(e) Earth

(f) The next generation

Answer :

(a) Effects of deforestation on wild animals:

Deforestation is the removal of trees or other vegetation from an area for industrial, agricultural, or other purposes. Trees and other

vegetation form the habitat of many animals. Hence, if the habitat of wild animals is destroyed, then their numbers would

automatically decline.

(b) Effects of deforestation on the environment:

Plants absorb CO2 from the atmosphere to perform photosynthesis. If plants are destroyed, then the level of CO2 in the atmosphere

will rise. As a result, CO2 will trap more heat radiations, thereby adding to global warming. An increase in the temperature of the

Earth will disturb the natural water cycle. As a result, there will be a change in the rainfall pattern. This could lead to floods or

droughts.

c) Effects of deforestation on villages:

Roots of plants hold soil particles together. In the absence of plants, the top layer of the soil will be easily removed by the action of

high speed winds or water flow. Thus, deforestation increases the chances of soil erosion. As a result, soil loses humus and become

less fertile. Hence, a fertile land, which is a source of living for farmers in villages, gets converted into a desert.

(d) Effects of deforestation on cities:

Deforestation in cities can increase the risk of many natural calamities such as floods and droughts in that area. Also, it can lead to

global warming due to an increase in the level of CO2 in the atmosphere as a result of vehicular and industrial pollution. This

increase in temperature can disturb the natural water cycle of an area

(e) Effects of deforestation on the Earth:

As a result of deforestation, chances of desertification, droughts, floods, etc. increase. Deforestation can also increase the level of

CO2 in the Earth. It will lead to an increase in temperature i.e., global warming. As a result, the entire natural water cycle will get

disrupted. This again increases the risk of natural calamities.

(f) Effects of deforestation on the next generation:

Deforestation is slowly changing our environmental conditions. It is responsible for global warming, soil erosion, greenhouse effect,

drought, floods, and many other global problems. As a result, the next generation will have to face severe consequences of

deforestation.

Q4 :

What will happen if:

(a) we go on cutting trees.

(b) the habitat of an animal is disturbed.

Answer :

(a) If we go on cutting trees, the natural habitat of many animals will get completely destroyed. As a result, the biodiversity of many

areas will be severely affected. Also, there will be an increase in the temperature of the Earth as a result of global warming, which

can disturb the natural water cycle. As a result, there will be a change in the rainfall pattern. This could lead to floods or droughts.

This will also increase the risk of soil erosion, desertification, and natural calamities.

(b) The habitat of an animal provides it with necessities such as shelter, food, and protection. If the habitat of an animal is disturbed,

then it will be forced to go to other places in search of food and shelter. The animal could get killed by other animals in this process.

(c) If the top layer of soil is exposed, then it will gradually expose the lower layer of soil, which is hard and rocky in nature. This type

of soil is less fertile as it contains less humus. Continued soil erosion will make the land barren or infertile.

Q5 :

Answer in brief:

(a) Why should we conserve biodiversity?

(b) Protected forests are also not completely safe for wild animals. Why?

(d) What are the causes and consequences of deforestation?

(e) What is Red Data Book?

(f) What do you understand by the term migration?

Answer :

(a) Biodiversity refers to the number and variety of various life forms such as plants, animals, and micro-organisms in an area.

Plants and animals depend on each other for survival. This means that the destruction of either of the two will affect the life of the

other. Hence, we need to conserve biodiversity to maintain the balance of nature.

(b) Protected forests are not completely safe for wild animals because people who live near or adjacent to forests use resources

from forests to fulfil their own requirements. In this process, wild animals are killed and sold for lucrative amounts of money.

(c) Tribals gather food, fodder, and fallen branches of trees from forests. Hence, they depend on forests for their daily requirements.

(d) Causes of deforestation:

(i) Forests are cleared for accommodating expanding urban areas and for fulfilling their ever-increasing requirements.

(ii) Forests are destroyed to clear land for crops and cattle grazing.

(iii) Trees are cut down to be used for firewood.

Consequences of deforestation:

(i) Soil erosion

(ii) Loss of biodiversity

(iii) Floods and droughts

(iv) Climate change due to global warming

(v) Disruption of water cycle

(e) Red Data Book is a source book that maintains an international list of all endangered animal and plant species. This book is

maintained by IUCN (International Union for Conservation of Nature and Natural resources).

(f) Migration refers to the movement of an organism or a group of organisms from its natural habitat to another place at a particular

time every year. Organisms migrate from one place to another to avoid inhabitable climatic conditions or for breeding.

Q6 :

In order to meet the ever-increasing demand in factories and for shelter, trees are being continually cut. Is it justified to cut

trees for such projects? Discuss and prepare a brief report.

Answer :

No. It is not at all justified to cut trees to meet the ever increasing demands of human population. Forests are the habitat of several

organisms including wild animals. They provide us with good quality air as they give out O2 and absorb the harmful CO2 gas from the

atmosphere. In the process, they prevent the excessive heating of the atmosphere. They prevent soil erosion and natural calamities

such as floods and droughts. They increase the fertility of the soil and help conserve biodiversity. The cutting of forests to meet the

demands of growing human population will lead to global warming, soil erosion, greenhouse effect, droughts, floods, and many

more problems. The destruction of forests will disturb the balance of nature. Hence, forests must be conserved.

Q7 :

How can you contribute to the maintenance of green wealth of your locality? Make a list of actions to be taken by you.

Answer :

I can help in maintaining the green wealth of my locality by taking care of the plants and trees growing in or around my locality. I can

plant more and more trees. I can also encourage the people in my locality to plant more trees by informing them about the

importance of growing trees. I can make young children aware of the effects that deforestation has on our environment and on ourplanet. I can also ask them to water the plants daily, which will take very little of their time. I believe planting new trees is as

important as taking care of the existing trees.

Q8 :

Explain how deforestation leads to reduced rainfall.

Answer :

Deforestation is the removal of trees or other vegetation from an area for industrial, agricultural, or other purposes. Plants or trees

absorb CO2 from the atmosphere. If plants are destroyed, then the level of CO2 in the atmosphere will rise. The high levels of CO2 in

the atmosphere will trap more heat radiations, leading to global warming. This increase in temperature of the Earth will disturb the

natural water cycle. As a result of disruption in the water cycle, there will be a change in the rainfall pattern. The reduced amount of

rainwater can cause droughts.

Q9 :

Find out about national parks in your state. Identify and show their location on the outline map of India.

Answer :

One of the national parks located near Delhi is the Corbett National Park.

Q10 :

Why should paper be saved? Prepare a list of ways by which you can save paper.

Answer :

Paper should be saved because it takes around seventeen full grown trees to make one tonne of paper. Trees, as we know, are

important to maintain a balance of nature. Therefore, in order to save trees and prevent the impact of their loss on living organisms,

we need to save paper.

Ways by which paper can be saved:

(i) Collect used paper and recycle it.

(ii) Use both sides of a paper for writing.

(iii) Spread awareness about the importance of paper.

(iv) Use paper intelligently.

Q11 :

Complete the world puzzle.

Down

1. Species on the verge of extinction.

2. A book carrying information about endangered species.

5. Consequence of deforestation.

Across

1. Species which have vanished.

3. Species found only in a particular habitat.

4. Variety of plants, animals and microorganisms found in an area.

Answer :

Down

1. ENDANGERED

2. RED DATA BOOK

5. DESERTS

Across

1. EXTINCT

3. ENDEMIC

4. BIODIVERSITY

____________________________________________________________________________________________

CH-8 Cell - Structure and Functions

Exercise : Solutions of Questions on Page Number : 98

Q1 :

Indicate whether the following statements are True (T) or False (F).

(a) Unicellular organisms have one-celled body. (T / F)

(b) Muscle cells are branched. (T / F)

(d) Amoeba has irregular shape. (T / F)

Answer :

(a) Unicellular organisms have one-celled body. (T)

(b) Muscle cells are branched. (F)

(d) Amoeba has irregular shape. (T)

Q2 :

Make a sketch of the human nerve cell. What function do nerve cells perform?

Answer :

The function of a nerve cell is to transmit messages to the brain and also to take away messages from the brain to the receptor

organs. Thus, it controls the working of different parts of the body.

Q3 :

Write short notes on the following.

(a) Cytoplasm

(b) Nucleus of a cell

Answer :

(a) Cytoplasm:

It is a fluid that fills the cell and occurs between the plasma membrane and the nucleus. Cell organelles such as mitochondria,

ribosomes, Golgi bodies, etc. are suspended in the cytoplasm. The cytoplasm helps in the exchange of materials between cell

organelles.

(b) Nucleus of a cell:

The nucleus is a spherical structure generally present at the centre of a cell. The nucleus is composed of the following components:

(i) Nuclear membrane:

It is a double-layered membrane which separates the contents of the nucleus from the cytoplasm. The nuclear membrane has

nuclear pores that allow the transfer of specific substances in and out of the nucleus.

(ii) Nucleolus:

It is a small spherical body that is not bound by any membrane.

(iii) Chromosomes:

These are thread-like structures that carry genes. Genes contain information necessary for the transfer of characteristics from the

parents to the offspring. Thus, chromosomes play an important role in the inheritance of characteristics.

Q4 :

Which part of the cell contains organelles?

Answer :

Cytoplasm is the part of the cell that contains various organelles such as mitochondria, ribosomes, Golgi bodies, etc. Cytoplasm is a

fluid that fills the cell and occurs between the plasma membrane and the nucleus.

Q5 :

State the difference between eukaryotes and prokaryotes.

Answer :

The nucleus contains thread-like structures called chromosomes. Chromosomes play an important role in the inheritance of

characters. They carry genes that help in the transfer of characters from the parents to the offspring.

Q7 :

'Cells are the basic structural units of living organisms'. Explain.

Answer :

Cells constitute various components of plants and animals. A cell is the smallest unit of life and is capable of all living functions.

Cells are the building blocks of life. This is the reason why cells are referred to as 'the basic structural and functional units of life'. All

cells vary in their shapes, sizes, and activities they perform. In fact, the shape and size of the cell is related to the specific function it

performs.

Q8 :

Explain why chloroplasts are found only in plant cells?

Answer :

Chloroplasts are found only in plant cells. They contain a green pigment called chlorophyll. This green pigment is important for photosynthesis in green plants. This chlorophyll pigment traps solar energy and utilizes it to manufacture food for the plant.

Q9 :

Complete the crossword with the help of clues given below.

Across

1. This is necessary for photosynthesis.

3. Term for component present in the cytoplasm.

6. The living substance in the cell.

8. Units of inheritance present on the chromosomes.

Down

1. Green plastids.

2. Formed by collection of tissues.

4. It separates the contents of the cell from the surrounding medium.

5. Empty structure in the cytoplasm.

7. A group of cells.

Answer :

Across

1. CHLOROPHYLL

3. ORGANELLE

6. PROTOPLASM

8. GENES

Down

1. CHLOROPLASTS

2. ORGAN

4. MEMBRANE

5. VACUOLE

7. TISSUE

Q10 :

Make sketches of animal and plant cells. State three differences between them.

Answer :

They are generally small in size. They are usually larger than animal cells.

Cell wall is absent. Cell wall is present.

Vacuoles are small in size. Vacuoles are larger in size.

No other animal cell possesses plastids

except for the protozoan Euglena.

Plastids are present.

____________________________________________________________________________________________

CH-9 Reproduction in Animals

Exercise : Solutions of Questions on Page Number : 110

Q1 :

Explain the importance of reproduction in organisms.

Answer :

Reproduction is a biological process through which living organisms produce offspring similar to themselves. Living organisms

reproduce to maintain their number and for the continuation of their species. Thus, reproduction ensures the continuation of similar

kinds of individuals.

Q2 :

Describe the process of fertilization in human beings.

Answer :

Fertilization involves the fusion of the male and the female gamete. The male and the female gametes are released from the male

and the female reproductive organs. Sperms or male gametes are released from the male reproductive organ i.e., the penis. These

sperms then enter the female body through the vagina. Then, they travel through the fallopian tubes where they meet the eggs.

Hence, the process of fertilization takes place in the fallopian tubes.

During fertilization, the haploid nucleus of the sperm and that of the ovum fuse with each other to form the zygote. This zygote

divides to form an embryo which in turn develops into a foetus.

Q3 :

Choose the most appropriate answer.

(a) Internal fertilization occurs

(i) in female body.

(ii) outside female body.

(iii) in male body.

(iv) outside male body.

(b) A tadpole develops into an adult frog by the process of

(i) fertilization

(ii) metamorphosis

(iii) embedding

(iv) budding

(i) none

(ii) one

(iii) two

(iv) four

Answer :

(a) (i) Internal fertilization occurs in the female body.

(b) (ii) A tadpole develops into an adult frog by the process of metamorphosis.

Q4 :

Indicate whether the following statements are True (T) or False (F).

(a) Oviparous animals give birth to young ones. ( )

(b) Each sperm is a single cell. ( )

(d) A new human individual develops from a cell called gamete. ( )

(e) Egg laid after fertilization is made up of a single cell. ( )

(f) Amoeba reproduces by budding. ( )

(g) Fertilization is necessary even in asexual reproduction. ( )

(h) Binary fission is a method of asexual reproduction. ( )

(i) A zygote is formed as a result of fertilization. ( )

(j) An embryo is made up of a single cell. ( )

Answer :

(a) Oviparous animals give birth to young ones. (F)

(b) Each sperm is a single cell. (T)

(d) A new human individual develops from a cell called gamete. (F)

(e) Egg laid after fertilization is made up of a single cell. (T)

(f) Amoeba reproduces by budding. (F)

(g) Fertilization is necessary even in asexual reproduction. (F)

(h) Binary fission is a method of asexual reproduction. (T)

(i) A zygote is formed as a result of fertilization. (T)

(j) An embryo is made up of a single cell. (F)

Q5 :

Give two differences between a zygote and a foetus.

Answer :

Zygote Foetus

It is a fertilized egg formed after the

fusion of the sperm with the egg.

It is a stage of the embryo that shows all the main

recognizable body parts of a mature organism.

The zygote divides several times to

form an embryo.

An embryo gradually develops into a foetus.

Q6 :

Define asexual reproduction. Describe two methods of asexual reproduction in animals.

Answer :

Asexual reproduction is a mode of reproduction that does not involve the fusion of the male and the female gamete. It requires only

one parent, and the offsprings produced are exact copies of their parents.

Two methods of asexual reproduction in animals are:

(i) Binary fission:

It is a type of asexual reproduction in which a single cell divides into two halves. Organisms that reproduce through binary fission

are bacteria and Amoeba. In Amoeba, the division of cells can take place in any plane. It involves the division of its nucleus into two

nuclei, which is followed by the division of its body into two halves. Each half of the body receives a nucleus.

(ii) Budding:

Budding involves the formation of a new individual from the bulges, known as buds formed on the parent body. This method of

reproduction is common in Hydra.In Hydra, thecells divide rapidly at a specific site and develop as an outgrowth, called the bud.

These buds, while being attached to the parent plant, develop into smaller individuals. When these individuals become mature

enough, they detach from the parent's body and become independent individuals.

Q7 :

In which female reproductive organ does the embryo get embedded?

Answer :

The embryo gets embedded in the wall of the uterus. The embryo while it is still attached to the uterus gradually develops various

body parts such as hands, legs, head, eyes, etc. The embryo is then called a foetus.

Q8 :

What is metamorphosis? Give examples.

Answer :

Metamorphosis is a biological process of transforming a larva into an adult. This involves relatively sudden and abrupt changes in

the animal's structure. Frogs and insects are examples of organisms showing metamorphosis. The life cycle of a frog has three

distinct stages:

EGG → TADPOLE → ADULT

The tadpole that emerges from the egg contains gills, a tail, and a small circular mouth. They can swim freely in water. The tadpole

grows and involves abrupt changes in its structure and develops into a mature frog. A tadpole's metamorphosis begins with the

development of limbs, lung development, and finally the absorption of the tail by the body.

Q9 :

Differentiate between internal fertilization and external fertilization.

Answer :

Internal fertilization External fertilization

It involves the fusion of the male and the

female gamete inside the female body.

It involves the fusion of the male and the

female gamete outside the female body.

Chances of the survival of the offspring are

more. Therefore, a small number of eggs are

Chances of survival of the offspring are produced.

less. Therefore, a large number of eggs are

produced.

Humans, cows, hens are organisms showing

internal fertilization.

Fish, frog, starfish are organisms showing

external fertilization

Q10 :

Complete the crossword puzzle using the hints given below.

Across

1. The process of the fusion of the gametes.

6. The type of fertilization in hen.

7. The term used for bulges observed on the sides of the body of Hydra.

8. Eggs are produced here.

Down

2. Sperms are produced in these male reproductive organs.

3. Another term for the fertilized egg.

4. These animals lay eggs.

5. A type of fission in amoeba.

Answer :

Across

1. FERTILIZATION

6. INTERNAL

7. BUDS

8. OVARY

Down

2. TESTIS

3. ZYGOTE

4. OVIPAROUS

5. BINARY

__________________________________________________________________________________________________________________________________________

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