Lakhmir Singh Manjit Kaur Class 10 Biology 5th Chapter “Our Environment” solution

Lakhmir Singh and Manjit Kaur Biology solution: “Our Environment” Chapter 5. Here you get easy solutions of Lakhmir Singh and Manjit Kaur Biology solution Chapter 5. Here we have given Chapter 5 all solution of Class 10. Its help you to complete your homework.

  • Board – CBSE
  • Text Book – Biology
  • Class – 10
  • Chapter – 05

Lakhmir Singh Manjit Kaur Class 10 Biology 5th Chapter Solution

Very short answer type questions

1.) What is the functional unit of the environment comprising of the living and non-living components called?

ANS- Ecosystem is the functional unit of environment which comprising living and no-living component.

2.) Name two natural eco-system and two artificial eco-systems

ANS-Natural ecosystems – Grass land, sea, forest

Artificial ecosystems – Parks, Gardens, aquarium, reservoirs

3.) Which one of the following is not a terrestrial ecosystem?

Forest, Grassland, Aquarium and Desert

ANS-Aquarium contains water as medium where whole ecosystem develops inside the water. Instead of that above all systems develops on land hence they are terrestrial ecosystem.

4.) Why plants are called producers?

ANS- Producers means the abject or matter which produces. A plant produces its own food by using water, sunlight, carbon dioxide that is the reason it called producer.

5.) What name has been given to those organisms, which break down the complex organic compounds present in dead animals and plants?

ANS- Decomposers are breaks down the organic compound which present in the dead animals and plant.

6.) What are planktons?

ANS- Planktons microscopic organisms also we called them algae which are autotrophic in nature and it freely floats on the surface of water, like pond, lake, river or ocean.

7.) State whether the following are true or false:

(a) In Biology human beings are called producers.


(b) Secondary consumers and tertiary consumers both are carnivores.


8.) Which category of organisms forms the starting point of a food chain?

ANS-producers are the start point from where the food chain starts.

9.) Which of the following belong to the same trophic level?

Goat, Spider, Plants, Hawk, Rat

ANS-Goat and Rat – herbivores

10.) Which of the following belong to the same trophic level?

Tree, Frog, Snake, Grass, Lizard

ANS-1) Tree and grass are producers

2) Frog, lizards and snakes are carnivores

11.) Write an aquatic food chain:


12.) Name the organisms belonging to the second and fourth trophic levels in the food chain comprising the following:Frogs, Plants, Snakes, Hawk, Insects

ANS- above food chain – plants       —->            insects       —->         frogs                snakes     —->         Hawks

From above food chain Second trophic level is Insects and Fourth trophic level: Snakes

13.) What are the various steps of food chain called?

ANS-  Steps involved in food chain called Trophic levels.

Example: plants        —->           insects       —->         frogs         —->       snakes     —->         Hawks.

Plant secure first tropic level, insect secure second tropic level, frog secure third tropic level etc.

14.) Construct a food chain comprising of the following:

Snake, Hawk, Rats, Plants

ANS- plants     —->           rats         —->        snake         —->         Hawk.

15.) Arrange the food chain:

Fish, Algae, Small animals, Big Fish

ANS-Algae Small animals Fish Big Fish

16.) Which organisms belong to the third and fourth trophic levels in the food chain comprising the following?

Rats, Plants, Hawk, Snake

ANS- Plants           —->          Rats           —->        Snake       —->           Hawk.

Third Trophic level: Snakes.

Fourth trophic level: Hawk.

17.) Which one term in the following includes the others?

Air, Flora, Fauna, Environment, Water, Sunlight, Soil

ANS-Air, Flora, Fauna, Water, Sunlight, Soil all terms comes under the Environment

18.) A food chain represents a unidirectional flow of X. What is X?


19.) Fill in the following blanks with suitable words:



(a) Specific.

(b) Producers.

(c) Food Chain.

(d) Ecology.

(e) Non – biodegradable; Biodegradable.

Short answer type questions

20.) Explain the terms producer and consumer. Give two examples of producers and two of consumers.


Producers –The organisms which made their own food by own way by using simple inorganic substance like water, sunlight, carbon dioxide and chlorophyll Example – Green plants and phytoplankton

Consumers-The organisms which depend on producers for food Example – Hawk, Bird

21.) Define decomposers.  Name one decomposer. (b) What is the role of decomposers in the ecosystem?


Decomposers-The micro-organisms which break down the complex organic material present in the dead organisms like dead plants and animals or we say the organism which feed on dead organisms called decomposers. Example – Fungus grows on bread.

(b) Role of decomposers- 1.) Ithelps to decompose the dead bodies of organism.

2.) Unknowingly it takes part in degradation process. Ultimately,environment gets clean.

22.) What is meant by a primary consumer, secondary consumer and tertiary consumer? Give one example of each.


1.) Consumers-the organisms which consumes food by others called consumers.

2.) Primary consumers-The organisms which depend on plants for their food is called Herbivores also it known as primary consumers. Example – Goat, deer, cattle

3.) Secondary consumers- The small carnivores which generally depend on herbivores or primary consumers for food is called as secondary consumers. Example – Frog

4.) Tertiary consumers- The Large carnivores which depend on small carnivores (secondary consumers) for food which we called tertiary consumers. Example – Tiger, Hawk, Lion

23.) Give an example of a four step food chain operating in grassland. Name the secondary consumer in this food chain.

ANS- grass        —>            insects        —>           frog          —>        snake

Here grass is the producer which makes its own food where the insects feed on the grass which we called herbivorus. Frog and snakes both are carnovorus but frog is secondary consumer which feed on herbivorus.

24.) (a) Define trophic level. Draw the food chain with four trophic levels.

(b) What will happen if we kill all the organisms in one trophic level?


(a) Trophic Levels – organisms eat food, from which it gets energy for various activities of body. So, the various types of organisms choose different- different type of food as per their body requirements. Organisms are depending on other living species for the purpose of food that is the reason one chain is form which we called food chain. many steps involved in food chain at which food get transfer from one to other organisms where the energy also get transfer from one level to other level those, we called trophic levels.

Tropic level also we called feeding level. That level we arrange like horizontal bar chart where the producer is the base with lengthy bar because it carries most of the energy where it reduces step by step up to top carnivores.

Example-In below Image Food chain and tropic levels pyramid.

(b) if organisms of any tropic level will die then our ecosystem get imbalance. The reason is that the tropic levels are made on the basis of need of food dependency on each other. If any tropic level gets destroy then the animals who feed on them get extinct due to starvation.


This is the one example of food chain  grass ——> deer——–> lion.

If it shown in the form of tropic level then it seems like

If the herbivores means deers will die then the carnivores ( Lion) which depends on them for food, are also die due to starvation. Herbivores are always eats grass, plants, etc. if they not alive then below thigs may get happens.

1. the population of plants get increase and ecosystem get affected.

2. the other way we say if plants quantity get increases then ultimately oxygen level on earth also get increases which cause fire on forest their also our environment and ecosystem faces harm.

25.) What is the difference between the food habits of organisms belonging to the first and the third trophic levels? Give one example each of the organisms belonging to these two trophic levels.

ANS- tropic levele means feeding level which always starts from producers and ends with the top carnivores.

From above tropic level we conclude that the producer is the first tropic level and carnvore is the third tropic level.

Difference between both is mainly bsed on their food habitat which shown in below table.



  1. It belongs to first tropic level
  1. It belongs to third tropic level

2. Food habitat-producers makes their food by own way by using inorganic subsatnce like water, carbon dioxide, sunlight, chlorophyll called as photosynthesis.

Example- grass, shrubs etc ( green plant)etc….

2. Food habitat- carnivores depends on herbivores for food.

Example- frog, tiger, lion etc….

26.) Can the organisms of any trophic level be removed without causing any damage to the ecosystem? Will the impact of removing all the organisms in a trophic level be different for different trophic levels?


No, because if any tropic level can remove, it affects the whole ecosystem.


If we removed second tropic level means indirectly, we removed deer population. Now the situation will happen that lion which depend on second tropic level (deer) get die due to starvation. Producer tropic level get increase because it is cannot be eaten by second tropic level. So, conclusion is that any tropic level gets removed then whole ecosystem suffers.

Yes, the impact of removing all the organisms of a trophic level will be different-different for different trophic levels.


If we removed second tropic level means indirectly, we removed deer population. Now the impact of that is….

  1. For third tropic level of organisms (carnivore) will die due to starvation- population decreases
  2. For first tropic level organisms(producers)- population increases

27.) Consider the food chain:

grass ——> deer——–> lion.

What will happen if all all the lions are removed from the above food chain?

ANS-If all the lions are removed from above chains then,

1.) The deer population get increases and they eat most of the grass that is the reason grass population get decreases.

2.) The animals which depend on grass other than deer are experiences starvation and they will die after sometime.

3.) Many organisms present in fauna and flora get extinct.

Due to above reasons whole ecosystem loses its balance.

28.) The number of malaria patients in a village  increased  tremendously when large number of frogs were exported from the village. What could be the cause for it?

ANS-malarial patients get increases it is sign of unbalancing ecosystem. Malaria cause due to host organisms called mosquito. Mosquito is the food of frog. Butfrog gets exported then mosquito population increases and this situation lead to for enhancing patients of malaria.

29.) How does a biodegradable waste differ from a non biodegradable waste?  Give two examples of non biodegradable waste which pollute our environment.


Bidegradable watse Non-biodegradable waste
1.       The material which easily breakdown in the soil by action of microbes called biodegradable wate 1.The material is not easily breakdown in the soil by action of microbes called non biodegradable waste.
2.       It is easily get degraded into soil without any causing pollution. is not degraded easily into soil and also it causes pollution in the environment
3.       These types of watse materials get recycled easily by natural way. 3.these type of waste recycled but it get takes many times also the recycle process is man made
4.       Example- paper,coconut material, wood materials, organisms dead body etc. 4.example-plastic material

30) Which of the following are biodegradable and which are non biodegradable?

glass bottle, paper, ballpoint pen refill, hay,  DDT, wheat, cake,wood,  polythene bag, jute bag, cotton cloth, grass,  vegetable peels.

ANS- Glass bottle – Non-biodegradable

Paper – Biodegradable

Ball point pen refill – Non- biodegradable

Hay – biodegradable

DDT – Non- biodegradable

Wheat – Biodegradable

Cake – Biodegradable

Wood – Biodegradable

Polythene Bag – Non-biodegradable

Jute Bag – Biodegradable

Cotton Cloth – Biodegradable

Grass – Biodegradable

Vegetable peels – Biodegradable

31.) (a) Describe an activity to show that while paper is biodegradable but plastic (say polythene)  is non-biodegradable.

 (b)  Explain why some materials are biodegradable but some are non biodegradable

ANS-(a) We done one activity from that we concluded the paper is biodegradable and plastic is non- biodegradable.


Step- 1.) We take a paper cup and plastic cup which is same in size.

2.) Buried them in the soil with same distance from the ground level.

Observation-After one month we observe those cups.

Paper cup is already starts degradation because it is eaten by microbes which are present in the soil but, Plastic cup is unaffected.

Conclusion-paper is biodegradable but plastic is non-biodegradable.

(b) Some materials are degradable and some are non-biodegradable which happens due to the action of microorganisms which feeds on them and breaks down the material. For example –when we buried plastic cup and paper cup in the soil after many months paper cup get starts to decompose but plastic is as it is in the soil. So basically non bio degradable material is not easily break by microbes hence its sustain as it is on the earth even after buried them.

32.) Write down food chain:

(a) in the sea

(b) which ends with humans

(c) with five links in it




33.) At which trophic level a person is feeding when he is eating:

(a) roasted chicken.  (b) bread. (c) eggs.  (d) apple.   (e) fish


(a) roasted chicken -third trophic level

(b) bread -Second trophic level

(c) eggs -Third trophic level

(d) apple -Second trophic level

(e) fish -Fourth trophic level

34.) A student went to study a local pond. In one part of the pond she noticed tadpoles scraping at some pond weed. In another part she saw a water beetle holding a tadpole in its jaw.

(a) Construct a food chain for the pond.

(b) How many links are there in this chain?


(a) Weed (producers) —> Tadpole (carnivores) —> Water beetle (carnivores)

(b) There are THREE links present in the above food chain.

35.) Construct (a) a short food chain,(b) a long food chain, and ending with man.



36.) (a) State one advantage of using jute bags over plastic bags for shopping.

(b) Write a common food chain of a pond ecosystem having four links.

ANS-(a) Jute bags are biodegradable that is why they not cause pollution.But, plastic bags are non-biodegradable hence they cause pollution.


37.) We do not clean ponds or lakes but an aquarium needs to be cleaned periodically. Why?

ANS- aquarium is compact manmade ecosystaem. But, pond lakes have natural ecosystem where all tropic levels are present like producers, herbivores, carnivores, decomposers .

Decomposers plays vital role in pond and lakes where ot decomposes dead bodies hence those aquatic system repeatedly get cleans up. But, in aquarium decomposers are absent hence decomposition also absent that is the reason this aquatic system is remain uncleaned.

38.) What will be the consequence of the absence of decomposers in the ecosystem?


1.) Decomposers plays major role to balance any kind of ecosystem by helping degradation in dead living species.

2.) Decomposers acts as ecosystem cleanser hence they are absent then dead bodies are remains same in the ecosystem and that is why environment experiences harms and untidyness.

3.) Decomposers are the main part of the ecosystem if it will absent then ecosystem experiences unstability.

39.) Give two differences between food chain and food web.

Food chain Food web
1. Food can be transferred from one organisms to other through food chain. 1. In food web, interconnected food chains are present.
2. Food chain is unidirectional. 2. Food web is multidirectional mesh where it shows interelationship with various species.

40.) Write one or two words for each of the statements / definitions:

(a) Each level of food chain where transfer of energy takes place.

(b) The physical factors like temperature, rainfall, light, soil, air and water of an ecosystem.

(c) Organisms which depend on the producers for food either directly or indirectly.

(d) The physical and biological world where we live in.

(e) Self-contained unit of living things and their non-living environment needing only sunlight for its functioning.


(a) Trophic Level

(b) The physical factors like temperature, rainfall, light, soil, air and water is the Abiotic components.

(c) Consumers are depends on the producers for food either directly or indirectly.

(d) Environment

(e) Ecosystem

Long Answer Type Questions

41.) (a) What is meant by biodegradeable waste materials? Give two examples of biodegradable wastes.

(b) Which of the folllowing materials are non- biodegradable?

Aluminium wire, Tea leaves, Synthetic fibre, Wool

ANS-(a) The material which easily breakdown in the soil by action of microbes called bio-degradable waste which is easily get degraded into soil without any causing pollution.Example -Paper and wood

(b) Aluminium wire and Synthetic fibre both are bon-biodegradable matter.

42) (a) What is meant by non-biodegradeable waste materials? Give two examples of non- biodegradable wastes.

 (b) Which of the following materials are biodegradable?

Animal bones, Iron nails, Plastic mugs, Leather belts, Silver foil

ANS-(a) The material is not easily breakdown in the soil by action of microbes called non biodegradable waste. Whenever its broken by some reason without any action of microorganisms then it cause it cause pollution. Example – Plastic and DDT powder

(b) Animal Bones and Leather Belts both are biodegradable materials.

43.) (a) Define an ecosystem. Give examples of any two ecosystems.

(b) List the biotic and abiotic components of an ecosystem.


Definition-An eco-system is a self-contained unit of living things (plants, animals and decomposers), and their non-living environment (soil, air and water).

1.) An ecosystem needs sunlight energy for their function.

2.) Ecosystem developed in on 1. Terrestrial as well aquatic level.

3.) Most of the ecosystems are natural but sometimes it may manmade

4.) Example – Grassland, a desert, crop field, forest, a mountain, a pond etc.


Biotic component – The biotic components means living things present in the ecosystem. Biotic community includes three types of organisms-producers, consumers and decomposers.

Abiotic components – The abiotic components meannon-living things present in the ecosystem. Abiotic component includes soil, water and air alongwith the in organic substances like carbon dioxide, nitrogen, water and phosphorous.

44.) (a) What is a food chain? Give one example of a simple food chain.

(b) What is a ‘food web’ ? Show its formation.


(a) Definition of food chain-The food or energy can be transferred from one organism to the other through the particular sequence which we called food chain. In that one organism eat or consumes other organisms.

Examples of simple food chain-




(b) Definition of food web-The interconnected food chains present in the ecosystem where the many food chains make mesh by showing interdependency between organisms is called a food web.

In above diagram

Many organisms feed on plants o grass where they both are producers. In other hand some organisms like insects are eaten by frog and hen. Ultimately we can say that hen and frogs are depends on insects hence more than one organisms depends on one organism for food. And that inter dependency makes mesh of food chain which known as food web.

45.) (a) What is meant by ‘environment’?

(b) What type of substances are the major pollutants of the environment?  Name two such substances.

(c) Name the organisms whose uncontrolled activities are damaging the environment.

(d) Explain why, it is better to use paper bags than plastic bags.


(a)The abiotic and biotic factors combine together is called environment.

(b) The non- biodegradable material causes pollution in environment because it cannot break down naturally. They need specific treatment for disposal. Even though they cause pollution in nature. Example-oil spilling in sea, chemical contamination on river, plastic and metal wires. If chemical contamination happens in river then many small molecules (any metal, harmful gases) get spread in environment those we called pollutants which causes pollution.

(c) Human beings are the only organisms whose always interfere in nature for their needs. Hence many natural things like ecosystem get unbalance also sometime pollution get because that is the reason environment get damage.

(d) Paper bags are biodegradable material it cannot cause pollution hence it is better to use paper bags for shopping.

2nd Part Solution

Very Short Type Questions

1.) What percentage of the solar energy is trapped and utilized by the plants?

ANS- 1% of the solar energy is trapped and utilized by the plants.

2.) What percentage of energy available at the producer level is transferred at successive trophic levels in a food chain?

ANS- Only  1% energy is trapped by plant which coming from sun but  from that  only 10% of energy is available with producer level and also is transfer successive level.

3.) Name the process in which a harmful chemical enters the food chain and gets concentrated at each trophic level.

ANS- Biological Magnification is the process in which harmful chemicals enters into food chain and concentrated at each tropic level.

4.) In a food chain consisting of grass, frog, bird and insects, where will the concentration of the harmful chemicals be maximum?


Grass —> insects  —> frog  —> bird  —> Chemical concentration getting increases

In above food chain of grass, frog, bird and insects where the bird is more affected from harmful chemicals because it is comes under last trpic level in this food chain so, more contamination seen on bird.

5.) If a harmful chemical enter a food chain comprising of cat, mice, and plants which on of these organisms is likely to have the maximum concentration of the harmful chemical in its body?

ANS- plants –> mice —> cat

From the above food chain plants is comes in first tropic level mice secure second tropic level and cat comes in the third tropic level hence it is very much affected in this food chain from chemicals.

6.) Which radiations are absorbed by the ozone layer?

ANS- ozone layer absorbed ultra-violet radiation.

7.) Name the group of chemical compounds which damages the ozone layer.

ANS- Chloro fluora Carbons which is the main pollutant damages the ozone layer.

8.) Name two waste materials which can be recycled.

ANS- Plastic and unwanted metal which can be recycled easily.

9.) Name the process by which the volume of solid waste can be reduced.

ANS-Incineration is the process by which solid waste can be reduced easily.

10.) If 5 joules of energy is available at producer level (plants), then how much energy will be transferred to the lion in the following food chain?

Plants ——> Goat ——> Lion

ANS- If 5 joules of energy is available at producer level which is here plant, from that it pass only 10% energy to goat that is 0.5 J of energy then  from that only 10 % energy is  transfer from goat to lion. Which is 0.05 J energy so, in above food chain lion is with 0.005 j of available energy.

11.) State whether the following statement is true or false;

Only 10 percent of the light energy given by the sun is available for transfer at each higher trophic level in a food chain.

ANS- False.

12.) Where does all the energy in living organisms originate from?

ANS-Sun is the main energy source from where the all energy in living organisms originated. Because all tropic levels start from the producers, so they take sunlight for energy purpose.

13.) Why are there rarely more than five links (or five organisms) in a food chain?

ANS-  Example- if we consider two food chain with three and four link.



See on above food chains a) in this chain snake is last link with 1 J of available energy.

b) In this food chain last link is peacock (which is 4th in number) with available energy 0.1.

according to energy law the energy gets reduced from one tropic level to another by 90% it means only 10% get transfer from one level to another.

So, from this above food chain we conclude that whenever the energy reached to last organism of food chain that time it gets decreases.So, less energy got to last organism which is not enough for sustain life of organism. That is the reason we cannot found more than five links in food chains or even it gets exist then it’s rare.

14.) Solution

(a) Cancer.

(b) Producer.

(c) Goat.

(d) Rabbit.

(e) Lion.

Short Answer Type Questions

16.) What is the percent law? Explain with an example.

ANS- PERCENT LAW- The studies of transfer of energy in different food chain in a large number of ecosystems has shown us the uniform pattern has been followed for energy transfer pattern which is we called percent law.This law is given by Lindeman in year 1942. Where it states that the energy gets reduced from one tropic level to another. So, in that law only ten per cent energy get transfer to one to another tropic level means the respective organisms got nine typer cent less energy than previous organisms.

Example –

Suppose we consider one food chain Grass —> mice —> snakes —> peacocks   where the grass is with 100 Joules available light energy.

If we apply ten per cent law for the below food chain then the energy got to mice from grass is 10 joules. Likewise, the energy available to snakes will be 10% of 10 joules which is 1 joule. So, the last organisms which is peacocks with o.1 joule which is 10% less than 1 joule.

17.) Write the full form of CFC. Give its one harmful effect.

ANS- 1.) CFC – Chlorofluorocarbons.

2.) Chlorofluorocarbon is very harmful to our environment. It is produces from various ways like by vehicles, refrigerator, AC etc. its pollutant which causes pollution.

3.) Cl, F is the harmful element which present in the chlorofluorocarbon.

Harmful effect-1) depletion of ozone layer

2) air pollution

3) Global warming

4) more U-V rays penetrate through ozone layer hence it easily enters on earth.

18.)  Explain how, harmful ultraviolet radiations of sunlight are prevented from reaching the earth’s surface.

ANS-Ozone layer is absorbing harmful ultraviolet radiation which coming from sun. Ozone layer is preventing many like1) skin cancer 2) eye disease called cataract 3)damage immune system

19.) What are the causes of depletion of ozone layer? Which diseases are likely to be caused if ozone layer will become thinner?

ANS-depletion of ozone layer leads to the many harmful effects, the main cause is that the harmful Ultraviolet rays is directly enter into the earth.

Biological cause- 1) skin cancer 2) eye disease 3) damage immune system by lowering the body’s resistance to the body

Non- biological cause-1) increases heat on earth 2) Global warming 3) south pole north pole get melt.

If the upper layer of ozone gets depleted due to chlorofluorocarbon hence we will may face 1) skin cancer 2) other body part get damages 3) damages the plant body

20.) Explain how harmful chemicals enter our bodies.

ANS- 1.) Harmful chemicals such as pesticides get entered into plant, animals and lastly humans. Chemicals enters into food chain through producers.

2.) harmful chemical get accumulate in food chain is called bio concentration of pesticides.

3.) pesticides are harmful chemical which spread on crop then it get absorb in their body or chemicals get accumulate in plant body. In this food chain plant is producer which is eaten by herbivore animals and it get further eaten by carnivore such away chemicals accumulate pass from one level to another tropic level.

4.) pesticides chemical on food chain-

21.) If we excessively use pesticides to protect the crops from diseases, then it may cause long term damage to mankind. Justify this statement.

ANS- Pesticides are made up of very harsh and poisonous chemical which is also non – biodegradable in nature. If we excessively use them then they show harm on our body because Humans comes under top tropic level In all food chain so more chemical get accumulate in human body.

Causes- 1.) Pesticide chemicals are harmful so they did not show sudden harm on body, these are damages body by gradually.

2.) DDT type harmful chemicals are accumulated in our whole ecosystem.

3.) may cause Heart stroke due to accumulation of metal chemicals, cancer, many diseases because which are related to the gradual change in human DNA.

22.) What is meant by biological magnification? With the help of a food chain, explain how biological magnification of harmful chemicals can occur.


Definition-The concentration of harmful chemicals increases in the body of living organisms at each trophic level of a food chain is called biological magnification. for example, chemicals present in the pesticides get concentrated by each level of food chain. So, the basically organism who acquire highest tropic level get more contaminated from harmful chemicals.

Explanation with diagram-In the below chain where the hawk is the last link organism who contaminated more than other three from harmful chemicals. If we consider the crop is with harmful chemical of pesticides which is eaten by mice and the mice get eaten by snake which also eaten by hawk. So, the higher tropic level animal is now hawk experiences more harmful effects.

Causes – above food chain get suffer due to more amount of chemical concentration such a way other food chain also suffers with the same problem. Food web get contaminated from that highest tropic level become more contaminated and they may extinct after some time due to health issues.

Bar graph of tropic levels according to above food chain.

From the above tropic diagram, we conclude that the top tropic level get more concentrated by chemicals which means there were we observe more biological magnification of chemicals.

23.) What is meant by bio concentration of pesticides? Which common pesticide has accumulated in human body in considerable amounts?


Pesticides are the full of harmful chemicals. If the concentrations of those chemicals (coming from pesticides) are accumulate and also increase in the organism’s body through the food chain is called bio concentration of pesticides.

1.) DDT is usually used as pesticides which have accumulated in human body through the food chain.

2.) Now a days UREA also uses on crop which is very harmful for body.

24.) What is garbage? What does garbage consist of?

ANS-1.) Definition of garbage-The household waste material is nothing but garbage.

2.) Garbage is consisting of wrappers, fruit peels, waste papers, plastic bags, potted plant, glass articles, metal objects, old wooden objects, rags, discarded shoes, and sewage

25.) What are the various modes of waste disposal?

ANS-Mostly wastes are two types one is dry wastes and wet wastes.

1.) In dry wastes contain plastics, rusted metals etc. those material get recycled for the disposal purpose.

2.) In wet waste contain fruit pills, waste vegetables etc. that can also reuse by forming themcompost.

Waste disposal methods shown below-

a) Recycling-solid waste like paper, plastics and metals are generally recycled.

b) preparation of compost-biodegradable domestic wastes such as left-over food, fruit and vegetable peels can be converted into compost by burying them in soil.

c) Incineration-incineration means waste substance burning at high temperature to form incineration.

d) Landfill-in this method waste can put in low-lying area of ground then it filled with soil called landfilling method.

e) sewage treatment-in this technique dirty drain water containing urine and faeces which is carried out from homes by the underground pipes.

26.) How can the waste such as paper, plastic and metal objects be disposed of?

ANS-papers, plastics and metals are the solid wastes which dispose by the recycling method where

1) paper is reprocessed to form new paper.

2) Plastic cups, broken plates, bottles are sent to metal industries where it gets melted and remoulded in the new useful material.

3) metals also recycled by sending it to metal industries where they may melt and recycled in solid metal material.

27.) Give a method of disposal of household wastes such as left-over food, fruit and vegetable peels and leaves of potted plants.

ANS- left over food, fruit, vegetables are biodegradable wastes. If we buried them properly then it will become a good compost and we easily used that as a manure such a way we disposed those kinds of bio-wastes.

28.) What is meant by incineration? For what purpose is it used?

ANS-Incineration means the waste materials get converts into ash, for that substance get burn at high temperature (more than 1000 degree Celsius) to form ash is called incineration.


1.) incineration method is used for destroy household waste; chemical waste biological wastes.

2.) Incineration method is help to reduce volume of waste.

29.) How are most of the solid wastes in urban areas disposed of?


1.) Urban area is the place which surrounded by a city. So, the population of this area is very big hence so many wastes are produces here and that can dispose by some specific methods.

2.) Landfilling is the method which is usually done in urban areas for waste disposal.

For that solid waste is dumped in the slope area and then that area starts to heal up. From this method uneven level of earth surface comes in even level after dumping this solid waste.

30.) State two advantages of using disposable paper cups over disposable plastic cups.


1.) Paper cups are biodegradable whereas Plastic cups are non-biodegradable.

2.) Paper cups does not cause pollution whereas plastic cups cause pollution.

3.) By burning of plastic cup, toxic gases get produce but paper cups does not produce any toxic gas by burning.

31.) What is sewage? How is sewage disposed of?

ANS-sewage is the dirty, waste water which produced from our homes. it contains urine and faeces and many semisolid as well solid wastes in the water medium.

Disposal- sewage disposed done on sewage disposed plant. For that underground pipes or sewers are duct system which carries sewage.

1.) Sewage treatment makes water clean which further get separated as a clean water into river.

2.) Solid or semisolid organic material which present in the sewage get ‘digested’ in sewage treatment by digester.

3.) During the sewage treatment particular type of gas get produces which we also called biogas.

Such away due to sewage treatment many clean substances get produced.

32.) Write harmful effects of ozone depletion.

ANS-U-V radiations are easily come to the earth when ozone gets depleted. This U-V radiation effects on many aspects like…

a) it can cause skin cancer

b) eye disease called cataract

c) damage immune system

d) south pole and north pole get melted

e) damages the plant body

33.) What would happen if the ozone layer in the atmosphere completely disappears?

ANS- If the ozone layer in the atmosphere disappears completely, then many harmful effects seen on flora and fauna.

1.) Harmful ultraviolet rays which coming from sun can come on earth easily.

2.) Earth seems much closer to sun

3.) Heat get increases on earth.

4.)  All harmful rays directly interact with organism’s body results human being faces skin cancer, eye damage, decrease power of immune system.

5.) Global warming

Long Answer Type Question

34.) (a) with the help of a flow diagram describe how energy from the sun flows through various trophic levels.

(b) Explain why, the flow of energy in the ecosystem is said to be unidirectional.

ANS- (a)

All organisms get energy from sun which is always transferring from tropic to tropic level. The food and energy is always going from producers to herbivores and from herbivores to carnivores. For that producers (means plants) get energy from sun and by using this energy, they make their own food. Herbivores depend on producers for food and carnivores depends herbivores such way energy also get transfer. This chain we have to elaborate below.

Plants –> herbivores –> carnivores

1.) The green plants makes their food by using solar energy for that water, carbon dioxide, and chlorophyll pigments takes part this process we called photosynthesis

Above glucose molecule is store in the leaves as energy source which is used by themselves for their body functions. Only 1% of the sun energy fall on leaves which is used for photosynthesis.From that some energy is utilized from the plant and remains energy stored as it is.

(b) Ecosystem developed as tropic to tropic level. For example, if we consider any food chain which exist in the aquatic system then we get total idea of energy transformation

In this above diagram algae are the producer which gain energy from sun for photosynthesis purpose. Herbivores can eat producers so, here protozoa is the herbivore which get energy from algae. Such a way the energy gets transfer from herbivore to carnivore. Every time that energy go from producer to carnivore. It never come back from carnivore to producers hence we called flow of energy is unidirectional in ecosystem.

35.) (a) What is ozone? How is it formed?

(b) How does ozone layer protect us from protect us for harmful effects in the environment?

(c) What is UNEP? What steps has been taken by UNEP in 1987 to prevent too much damage to the ozone layer?


(a) Ozone is milky fog layer spread over on earth. It is formed by three atoms of oxygen. When O2 molecule splits up by UV rays that time free atom of oxygen get form.

See the below reaction.

UV rays bombard on O2 molecule.

In this below reaction O2 molecule reacts with free oxygen atom develops ozone layer.

O + O2 —> O3

(b) Ultraviolet radiations absorb by ozone layer hence harmful effects on environment is not happened.

(c) UNEP means United Nation Environment Program.

Ozone layer is depleting so many causes will happen hence that UNEP program were run.

1.) Motivation of this program to prevent ozone layer.

2.) For that United Nations Environment Program (UNEP) forged an agreement among its member countries to freeze CFC production in 1986.

36.) (a) How is energy introduced into the ecosystem?

(b) Consider the following food chains:

(i) Plants ——> Mice ——-> Snakes ——> Hawks

(ii) Plants —–> Mice ——-> Hawks

If energy available at the producer level in both the food chains is 100 J, in which case will hawks get more energy as food and by how much? Justify your answer.

ANS-(a) All ecosystems are energizing by food and sunlight. Ecosystem get starts from the producers which are green plant. They make their own food by own way by taking energy from the sun. So, due to photosynthesis energy get enter into the ecosystem.

Above reaction is showing photosynthesis of plant where it takes light energy from sunlight and make its own food hence the producers only introduce energy in ecosystem.

(b) (i) plant is the producer in above food chain where we consider 100 J available in plants as food. If we apply 10% law to both above food chain: then by calculation energy get reduced in both food chains

Explanation- above 1) and 2) chain shows availability of energy in each tropic level.

1.) 100 J energy is present in the plant from which only 10% energy passes to mice so, 10 J energy got to mice which is seen in both 1) and 2) food chain.

2.) 10 J energy is present in the mice from which only 10% energy passes to snakes so, 1 J energy got to snakes.

3.) In first food chain snake is the third link so it get 1J of available energy and hawk get 10% from that means 0.1 J of energy. Whereas, in second food chain third link is hawk so it survive with 1 J of available energy

CONCLUSION- Second food chain is with only three links that is why hawk get 1J of available energy.

But, first food chain is with four links hence Hawk gets 0.1 J of available energy.

So Hawk which is in second food chain gets more energy than first food chain.

1 J -0.1 J =0.9 J

Hence hawk in second food chain get 0.9 J of extra energy than first food chain.

37.) (a) Explain why, a food chain usually cannot have more than three or four steps.

(b) Calculate the amount of energy that will be available to big fish in the following food chain, if 10,000 J of energy is available to small algae from the sun:

Small Algae ——-> Zooplankton —–> Fish ——> Big fish

ANS-(a) Food chain is made to survival of organisms where they are depends on each other for food or we say energy is get transfer from the tropic to tropic level. So while transferring this energy get reduced. Only 10 % energy get transfer from one level to other that is why for the last level it can’t enough hence food chain usually cannot have more than three or four steps..  For example-

If we compare above food chain then 1st food chain with four link where the hawk get 0.1 J of energy. But in second 2) food chain hawk is under third tropic level so, hawk got 1 J of energy.

Conclusion- according to energy law the energy gets reduced from one tropic level to another by 90% it means only 10% get transfer from one level to another.

So, from this above food chain we conclude that whenever the energy reached to last organism of food chain that time it gets decreases. So, less energy got to last organism which is not enough for sustain life of organism. That is the reason we cannot found more than five links in food chains or even it gets exist then it’s rare.

(b) 1.) In above diagram 10,000 J of energy is available to sun from that 1% of energy fall on algae. So now, algae are with 100 J of energy.

2.) Zooplanktons are depending on the algae for food that is why it got 10 J of energy from the algae which is 10% part of its own available energy.

3.) Zooplankton transfer energy to fish. So, fish is with 1 J of energy which is also 10% of available energy of zooplankton.

4.) Big fish got 0.1 J of energy which is 10% of fish energy.


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Updated: May 28, 2022 — 4:08 pm

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