CBSE Class 10 Science — Our Environment

An ecosystem contains maximum number of:

Which of the following is a non-biodegradable pollutant?

The reasons for excessive generation of wastes are: (i) Use and throw policy. (ii) Increased availability of packaged food. (iii) Increased construction wastes. (iv) Non-sorting of dry and wet wastes. Select the correct combination of options.

Which of the following group is not 'biodegradable'?

Given below is a pyramid showing various trophic levels in an ecosystem: (a) From the organisms listed below, identify which one is to be placed at which trophic level? Deer, Grass, Lion, Snake, Rabbit (b) Discuss the reason why primary consumers will have more energy as compared to secondary consumers? (c) Why is the base of the pyramid broad?

(a) Mention any one harmful effect of using plastic bags on the environment. Suggest better alternatives to the usage of plastic bags. (b) Paddy fields require a large amount of water. The pesticides and chemical fertilizers used are washed down into the soil or waterbodies. How do these chemicals reach our bodies? What is this phenomenon known as?

Which of the following groups do not constitute a food chain ? (i) Wolf, rabbit, grass, lion (ii) Plankton, man, grasshopper, fish (iii) Hawk, grass, snake, grasshopper, frog (iv) Grass, snake, wolf, tiger

In the food chains given below. Select the most efficient food chain in terms of energy :

The examples of natural and manmade (artificial) ecosystems are respectively

Consider the following food chain: Grass -> Grasshopper -> Frog -> Snake -> Eagle. If the amount of energy available at third trophic level is $50 \text{ kJ}$, the available energy at the producer level was:

The percentage of solar energy which is not converted into food energy by the leaves of green plants in a terrestrial ecosystem is about :

The incorrect statement about ozone is:

Which one of the following gets biomagnified at different levels in a food chain?

Human activities that are affecting the environment are :

Other than the abiotic components, which of the given biotic components are not required to make an aquarium with small herbivorous fishes a self-sustaining system? (i) Aquatic plants and aquatic animals (ii) Terrestrial plants and terrestrial animals (iii) Decomposers as bacteria and fungi (iv) Consumers as clown fishes and sea urchins

Identify from the following a group containing all non-biodegradable substances.

Assertion (A): Use of jute bags for shopping reduces pollution. Reason (R): Jute is biodegradable and its bag may be reused as and when needed.

Assertion (A) : The amount of ozone in the atmosphere began to drop sharply in the 1980s. Reason (R) : The oxygen atoms combine with molecular oxygen to form ozone.

Assertion (A): Food web is a network of several food chains operating in an ecosystem. Reason (R): Food web decreases the stability of an ecosystem.

We do not clean natural ponds or lakes whereas an aquarium or a swimming pool needs to be cleaned regularly. Why?

"Excessive use of chemicals and pesticides in agriculture adversely effect the environment." Justify this statement.

(a) Why are the organisms of first trophic level important in any food chain? (b) Justify the following statement: 'The flow of energy in an ecosystem is unidirectional.'

What are decomposers? Give two examples. State how they maintain a balance in an ecosystem.

(a) "In a food chain energy flow is unidirectional." Give two reasons for the given statement. (b) If 10,000 J energy is available at the producer level, how much energy will be available to the secondary consumers? Give reason to justify your answer.

Write the essential function performed by ozone at the higher levels of the atmosphere. How is it formed in the upper atmosphere? Write the name of the group of chemicals mainly responsible for the depletion of ozone layer.

A food chain will be more advantageous in terms of energy if it has

Consider the following statements about ozone: (a) Ozone is poisonous gas. (b) Ozone shields the earth's surface from the infrared radiation from the sun. (c) Ozone is a product of UV radiations acting on oxygen molecule. (d) At the lower level of the earth's atmosphere, ozone performs most essential function. The correct statements are

Which one of the following is not a natural ecosystem ?

Some wastes are given below : (i) Garden waste (ii) Ball point pen refills (iii) Empty medicine bottles made of glass (iv) Peels of fruits and vegetables (v) Old cotton shirt. The non-biodegradable wastes among these are :

Assertion (A): The waste we generate daily may be biodegradable or non-biodegradable. Reason (R): The waste generated, if not disposed off properly may cause serious environmental problems.

Assertion (A): Ozone layer protects the surface of the Earth from harmful UV radiations. Reason (R): Chlorofluorocarbons (CFCs) are responsible for depletion of ozone layer.

What are decomposers? List two consequences of their absence in an ecosystem.

Name the term used for the materials which cannot be broken down by biological processes. Give two ways by which they harm various components of an ecosystem.

Use of pesticides to protect our crops affect organisms at various trophic levels especially human beings. Name the phenomenon involved and explain how does it happen.

(A) Plants $\rightarrow$ Deer $\rightarrow$ Lion In the given food chain, what will be the impact of removing all the organisms of second trophic level on the first and third trophic level? Will the impact be the same for the organisms of the third trophic level in the above food chain if they were present in a food web? Justify. OR (B) A gas 'X' which is a deadly poison is found at the higher levels of atmosphere and performs an essential function. Name the gas and write the function performed by this gas in the atmosphere. Which chemical is linked to the decrease in the level of this gas? What measures have been taken by an international organization to check the depletion of the layer containing this gas?

Differentiate between food chain and food web. In a food chain consisting of deer, grass and tiger, if the population of deer decreases, what will happen to the population of organisms belonging to the first and third trophic levels?

Study the picture given below showing three food chains (a), (b) and (c) and answer the following questions: (i) Name the type of ecosystems that exist in food chains (b) and (c). (ii) The first trophic level in all food chains are producers. Why? What percentage of solar energy do these producers capture for their use? (iii) Why are the arrows shown in the diagram in one direction only and not vice versa? Justify.

Assertion (A) : The energy which passes to the herbivores does not come back to autotrophs. Reason (R) : The flow of energy in a food chain is unidirectional.

In the following food chain, if 50 J of energy was available to the hawk, how much energy would have been present at the first and third tropic levels? Justify your answer. Grass $\longrightarrow$ Grasshopper $\longrightarrow$ Frog $\longrightarrow$ Snake $\longrightarrow$ Hawk

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

Use of several pesticides which results in excessive accumulation of pesticides in rivers or ponds, is a matter of deep concern. Justify this statement.

How do harmful chemicals get accumulated progressively at each trophic level in a food chain?

(a) Write the percentage of (i) solar energy captured by the autotrophs and (ii) energy transferred from autotrophs to the next level in a food chain. (b) What are trophic levels? Why do different food chains in an ecosystem not have more than four to five trophic levels? Give reason.

How is ozone formed in the higher levels of the atmosphere? "Damage to the ozone layer is a cause of concern." Justify this statement.

Write one difference between biodegradable and non-biodegradable wastes. List two impacts of each type of the accumulated waste on environment if not disposed off properly.

Explain how some harmful chemicals enter our bodies through the food chain. Why is the concentration of these harmful chemicals found to be maximum in human beings?

(a) (i) Why does a kitchen garden called an artificial ecosystem while a forest is considered to be a natural ecosystem? (ii) While designing an artificial ecosystem at home, write any two things to be kept in mind to convert it into a self-sustaining system. Give reason to justify your answer. OR (b) (i) Construct a food chain of four trophic levels comprising the following: Hawk, snake, plants, rat. (ii) 20,000 J of energy was transferred by the producers to the organism of second trophic level. Calculate the amount of energy that will be transferred by organisms of the third trophic level to the organisms of the fourth trophic level.

(a) Kulhads (disposable cups made of clay) and disposable paper cups both are used as an alternative for disposable plastic cups. Which one of these two can be considered as a better alternative to plastic cups and why?

(b) Human beings are most adversely affected by the Biological Magnification. State the reason. Why can ordinary washing of the edibles (fruits and vegetables) not reduce the effect of biological magnification?

"The improvement in our lifestyle has led to the generation of large amount of waste material." List two reasons to justify this statement. OR "The change in packaging has resulted in waste becoming non-biodegradable." Giving two examples from daily life, justify this statement.

In the following food chain, only $2\text{J}$ of energy was available to the peacocks. How much energy would have been present in Grass? Justify your answer. GRASS $\rightarrow$ GRASS HOPPER $\rightarrow$ FROG $\rightarrow$ SNAKE $\rightarrow$ PEACOCK

OR (a) What is meant by garbage? List two classes into which garbage is classified. (b) What do we actually mean when we say that the "enzymes are specific in their action"?

(a) What is ozone ? How is it formed in the upper layers of the Earth's atmosphere ? How does ozone affect our ecosystem ? OR (b) (i) List two human-made ecosystems. (ii) "We do not clean a pond in the same manner as we do in an aquarium." Give reason to justify this statement.

What are human-made ecosystems? Give an example. Can a human-made ecosystem become a self-sustaining ecosystem? Give reason to justify your answer.

What are trophic levels? Why are autotrophs considered to be at the first trophic level of all food chains? State the reason for limited number of trophic levels in nature.

(a) Name the group of organisms which form in the first trophic level of all food chains. Why are they called so? (b) Why are the human beings most adversely affected by bio-magnification? (c) State one ill-effect of the absence of decomposers from a natural ecosystem.

(a) We do not clean ponds or lakes, but an aquarium needs to be cleaned regularly. Why? (b) Why is ozone layer getting depleted at the higher levels of the atmosphere? Mention one harmful effect caused by its depletion.

Answer question numbers 3(a) to 3(d) on the basis of your understanding of the following paragraph and the related studies concepts. The Tehri dam is the highest dam in India and one of the highest in the World. The Tehri dam withholds a reservoir of capacity $4.0 \text{ km}^3$ and surface area $52 \text{ km}^2$. It is used for irrigation, municipal water supply and the generation of 1000 MW of hydro electricity. The Tehri Dam has been the object of protests. Environment activist Shri Sunder Lal Bahuguna led the "Anti Tehri Dam Movement" from 1980s to 2014. The protest was against the displacement of town inhabitants and environmental consequences of the weak ecosystem. The relocation of more than 1,00,000 people from the area has led to protracted legal battles over resettlement rights and ultimately resulted in the delayed completion of the project. (a) How is hydropower harnessed? (b) Define 1 MW. (c) Mention two disadvantages of constructing Tehri Dam. (d) What happens when water from great heights is made to fall on blades of turbine?

Answer question numbers 3(a) – 3(d) on the basis of your understanding of the following paragraph and the related studied concepts: Solar power in India is a fast developing industry. The country's solar installed capacity reached $30.071 \text{ GW}$ as of 31 July, 2019. India has the lowest capital cost per MW to install solar power plants. Solar electricity generation recorded nearly $3.4\%$ of total utility electricity generation in January 2019. The following table shows Annual Solar Power Generation of the last six years. Year | Solar Power Generation (TWh) 2013 – 14 | 3.35 2014 – 15 | 4.60 2015 – 16 | 7.45 2016 – 17 | 12.09 2017 – 18 | 25.87 2018 – 19 | 39.27 Our country is lucky to receive solar energy for the greater part of the year. It is estimated that during a year India receives the energy equivalent to more than $5000 \text{ trillion kWh}$ from the Sun. 3(a) What are solar cells? 3(b) How much voltage can be developed and how much electricity can be produced by one typical solar cell when exposed to the Sun? 3(c) The future of power generation by solar energy is bright in India. Give reason. 3(d) List two advantages of solar cells.

Answer question numbers 4(a) – 4(d) on the basis of your understanding of the following paragraph and the related studied concepts: India today is facing the problem of overuse of resources, contamination of water and soil and lack of methods of processing the waste. The time has come for the world to say goodbye to "single-use plastics". Steps must be undertaken to develop environment-friendly substitutes, effective plastic waste collection and methods of its disposal. Indore treated 15 lakh metric tonnes of waste in just 3 years, through biomining and bioremediation techniques. Bioremediation involves introducing microbes into a landfill to naturally 'break' it down and biomining involves using trommel machines to sift through the waste to separate the 'soil' and the waste component. The city managed to chip away 15 lakh metric tonnes of waste at a cost of around ₹ 10 crore. A similar experiment was successfully carried out in Ahmedabad also. 4(a) State two methods of effective plastic waste collection in your school. 4(b) Name any two uses of "single-use plastic" in daily life. 4(c) If we discontinue the use of plastic, how can an environment-friendly substitute be provided? 4(d) Do you think microbes will work similarly in landfill sites as they work in the laboratory? Justify your answer.

A diagram of traditional water harvesting system is given. The statement which defines the system and its parts is: OR The major ill effect of mono culture practice in forests is on the:

Which of the following are water intensive crops?

The most poisonous product formed by incomplete combustion of fossil fuels is

Consider the following criticisms that are generally addressed when a new project is launched : I. Displacement of peasants and local tribals without compensation. II. Swallowing up large amount of public money without any benefits. III. Deforestation and loss of biodiversity. The criticisms about large dams in particular are

OR Switching off unnecessary lights and fans and repairing leaking taps correctly defines which term of 5R's ?

Bandharas and Tals are age old water harvesting concepts / structures found in

The Reni village of Garhwal is famous for

Which one of the following statements is not true about nuclear energy generation in a nuclear reactor? (A) Energy is obtained by a process called nuclear fission. (B) The nucleus of Uranium is bombarded with high energy neutrons. (C) A chain reaction is set in the process. (D) In this process a tremendous amount of energy is released at a controlled rate. OR The biggest source of energy on Earth's surface is

Food web is constituted by

Choose the incorrect statement from the following:

OR Complete the following flow chart based on ecosystem and its components.

(a) Construct a terrestrial food chain comprising four trophic levels. (b) What will happen if we kill all the organisms in one trophic level? (c) Calculate the amount of energy available to the organisms at the fourth trophic level if the energy available to the organisms at the second trophic level is 2000 J.

What is meant by trophic level in a food chain ? Construct a terrestrial food chain with four trophic levels. The energy flow in a food chain is always unidirectional. Why ?

OR: (a) Complete the following table: Oxygen, Ozone, Formula, (i), (ii), Benefits to biotic component, (iii), (iv). (b) How is ozone formed at the higher levels of atmosphere?

(a) From the following group of organisms create a food chain which is the most advantageous for Human beings in terms of energy. (b) State the possible disadvantage if the cereal plant is growing in soil rich in pesticides. (c) Construct a food web using the organisms mentioned above. OR (a) Write two harmful effects of using plastic bags on the environment. Suggest alternatives to the usage of plastic bags. (b) List any two practices that can be followed to dispose off the waste produced in our homes.

Why is biogas considered an excellent fuel?

Write the energy conversion that takes place in a hydropower plant.

Students in a school listened to the news read in the morning assembly that the mountain of garbage in Delhi, suddenly exploded and various vehicles got buried under it. Several people were also injured and there was traffic jam all around. In the brain storming session the teacher also discussed this issue and asked the students to find out a solution to the problem of garbage. Finally they arrived at two main points – one is self management of the garbage we produce and the second is to generate less garbage at individual level. (a) Suggest two measures to manage the garbage we produce. (b) As an individual, what can we do to generate the least garbage? Give two points. (c) List two values the teacher instilled in his students in this episode.

What is a dam? Why do we seek to build large dams? While building large dams, which three main problems should particularly be addressed to maintain peace among local people? Mention them.

In the following food chain, 20,000 J of energy was available to the plants. How much energy would be available to man in this chain? Plants → Sheep → Man

You being an environmentalist are interested in contributing towards the conservation of natural resources. List four activities that you can do on your own.

Why are coal and petroleum categorised as natural resources? Give a reason as to why they should be used judiciously.

Why is an equitable distribution of resources essential in a society ? List two forces which are against such distribution.

Why must we conserve our forests ? List two factors responsible for causing deforestation.

(a) Water is an elixir of life, a very important natural resource. Your Science teacher wants you to prepare a plan for a formative assessment activity, “How to save water, the vital natural resource”. Write any two ways that you will suggest to bring awareness in your neighbourhood, on ‘how to save water’. (b) Name and explain any one way by which the underground water table does not go down further.

“What was Chipko Andolan”? How did this Andolan ultimately benefit the local people and the environment?

“Burning of fossil fuels results in global warming”. Give reasons to justify this statement.

Write one negative effect, on the environment, of affluent life style of few persons of a society.

In a food chain of frog, grass, insect and snake, assign trophic level to frog.

List four stakeholders which may be helpful in the conservation of forests.

Forests are “biodiversity hot spots”. Justify this statement.

The construction of large dams leads to social and environmental problems. List two problems of each category.

What is water harvesting? How can this technique help in the conservation of water?

The activities of man had adverse effects on all forms of living organisms in the biosphere. Unlimited exploitation of nature by man disturbed the delicate ecological balance between the living and non-living components of the biosphere. The unfavourable conditions created by man himself threatened the survival not only of himself but also of the entire living organisms on the mother earth. One of your classmates is an active member of 'Eco club' of your school which is creating environmental awareness amongst the school students, spreading the same in the society and also working hard for preventing environmental degradation of the surroundings. (a) Why is it necessary to conserve our environment? (b) State the importance of green and blue dust-bins in the safe disposal of the household waste. (c) List two values exhibited by your classmate who is an active member of Eco-club of your school.

What is the function of ozone in the upper atmosphere?

Why are forests considered “biodiversity hot spots”? List two ways in which an individual can contribute effectively to the management of forests and wildlife.

What is meant by “sustainable management”? Why is reuse considered better than recycling?

After the examinations Rakesh with his friends went on a picnic to a nearby park. All friends carried cooked food packed in plastic bags or plastic cans. After eating the food some friends collected the leftover food and plastic bags etc and planned to dispose them off by burning. Rakesh immediately checked them and suggested to segregate the leftover food and peels of fruits from the plastic materials and respectively dispose them off separately in the green and red dustbins placed in the corner of the park. (a) In your opinion, is burning plastic an eco-friendly method of waste disposal? Why? State the advantage of method suggested by Rakesh. (b) How can we contribute in maintaining the parks and roads neat and clean?

What are hot spots inside earth's crust?

Amit lives in Delhi and is much concerned about the increasing electricity bill of his house. He took some steps to save electricity and succeeded in doing so. (i) Mention any two steps that Amit might have taken to save electricity. (ii) Amit fulfilled his duty towards the environment by saving electricity. How? (iii) Which alternative source of energy would you suggest Amit to use?

List any three qualities of an ideal source of energy.

Why should biodegradable and non-biodegradable wastes be discarded in two separate dust bins?

We often observe domestic waste decomposing in the bylanes of residential colonies. Suggest ways to make people realise that the improper disposal of waste is harmful to the environment.

(a) What is an ecosystem? List its two main components. (b) We do not clean ponds or lakes, but an aquarium needs to be cleaned regularly. Explain.

What is the function of ozone at the higher level of atmosphere?

What happens when higher energy ultraviolet radiations act on the oxygen at the higher level of the atmosphere ?

Which class of chemicals is linked to the decrease in the amount of ozone in the upper atmosphere of the earth ?

Consider the following food chain which occurs in a forest: Grass → Deer → Lion. If 10000 J of solar energy is available to the grass, how much energy would be available to the deer to transfer it to the lion?

Bacteria and fungi are called decomposers. Why ?

In a food chain, if 10,000 joules of energy is available to the producer, how much energy will be available to the secondary consumer to transfer it to the tertiary consumer ?

List three problems which arise due to construction of big dams. Suggest a solution for these problems.

List four advantages of water stored in the ground.

Why are forests considered “biodiversity hot spots”? List two ways in which an individual can effectively contribute to the management of forests and wildlife.

State the meaning of “sustainable management”. Reuse is better than recycling. How?

“Burning fossil fuels is a cause of global warming.” Justify this statement.

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

Why is decrease of ozone in our ozone layer a cause for our worry ?

Why are bacteria and fungi called decomposers ?

Define : (i) Biomass (ii) Anaerobic degradation

What are non-renewable resources of energy? Give two examples of such resources.

What is an equitable distribution of resources in a society and why is it necessary ? State any two factors which work against an equitable distribution of resources.

What is the main constituent of biogas ? How is biogas obtained from biomass ? Write any two advantages of using this gas.

Mention any four limitations in harnessing wind energy on a large scale.

How is the increasing demand for energy adversely affecting our environment?

Explain the phenomenon of “biological magnification.” How does it affect organisms belonging to different trophic levels particularly the tertiary consumers ?