NCERT Solutions for Class 10 Science Chapter 15 Our Environment

The Class 10 NCERT Solutions for Science Chapter 15 Our Environment includes all the intext and exercise questions. Class 10 Science Chapter 15 Our Environment NCERT questions and answers help students to clear their doubts and to obtain good marks in Class 10 board exam. All the solutions provided in this article are strictly based on the CBSE syllabus and curriculum.

Class 10 Science Chapter 15 NCERT Questions and Answers

Class 10 Science Chapter 15 Our Environment NCERT Questions and Answers are prepared by experts with a detailed explanation that will help students complete their assignments & homework. Having a good grasp over CBSE NCERT Solutions for Class 10 Science will further help the students in their preparation for board exams and other competitive exams such as NTSE, Olympiad, etc.

NCERT Solutions for Class 10 Science Chapter 15 Intext Questions

Intext Question (Page No. 260)

Question 1: What are trophic levels? Give an example of a food chain and state the different trophic levels in it.

Answer: The various steps in food chain at which transfer of food energy takes place are called trophic levels.
Food chain operating in a grassland.
Grass → Insects → Frogs → Snakes

  1. Grass → 1st trophic level
  2. Insects → 2nd trophic level
  3. Frogs → 3rd trophic level
  4. Birds → 4th trophic level

Question 2: What is the role of decomposers in the ecosystem?

Answer: Following is the role of a decomposer in the ecosystem:

  • They act as a cleansing agent of the environment by decomposing the dead plants and animals
  • They help in recycling the nutrients
  • They provide space for new beings in the biosphere by decomposing the dead
  • They help in putting back the various elements into water, soil and air for the reuse of producers like crop plants.

Intext Question (Page No. 262)

Question 1: Why are some substances biodegradable and some non-biodegradable?

Answer: Some substances which are degraded and broken down into simpler substances by the microorganisms, are called biodegradable substances.

For example: Cotton, wood, paper, wool, etc.

Substance (mainly man-made) that do not degrade or broken down into simpler substances by the action of enzymes secreted by microorganisms are called non- biodegradable substances.

For example: Plastic, polythene, DDT, etc.

Question 2: Give any two ways in which biodegradable substances would affect the environment.


  • During decomposition process of biodegradable substances foul smell and some harmful gases are released which make problem for the nearby living person.
  • During decomposition it provide a breeding ground for mosquitoes, insects and microbes responsible for diseases like cholera, diarrhoea, etc.

Question 3: Give any two ways in which non-biodegradable substances would affect the environment.

Answer: Following are the ways in which non-biodegradable substances would affect the environment:

  • Chemicals like BHC and DDT induce carcinoma (muscle cancer) and growth of tumours.
  • Handling of waste materials may cause skin, respiratory and intestinal infections.
  • Non-biodegradable substances do not decompose easily so it produces land and water pollution.

Intext Question (Page No. 264)

Question 1: What is ozone and how does it affect any ecosystem?

Answer: Ozone (O3) is a molecule formed by three atoms of oxygen. Ozone, is a deadly poison. However, at the higher levels of the atmosphere, ozone performs an essential function. It shields the surface of the earth from ultraviolet (UV) radiation from the Sun. This radiation is highly damaging to organisms, for example, it is known to cause skin cancer, cataract and damage the immune system in human beings. It also destroys plants and reduces photosynthesis process.

Question 2: How can you help in reducing the problem of waste disposal? Give any two methods.


  • By minimizing the use of disposal items and promoting the use of recycled articles.
  • Separating biodegradable and non-biodegradable waste before dumping them.
  • Recycling the non-biodegradable waste material.

NCERT Solutions for Class 10 Science Chapter 15 Exercise Questions

Question 1: Which of the following groups contain only biodegradable items?

(a) Grass, flowers and leather
(b) Grass, wood and plastic
(c) Fruit peels, cake and lime juice
(d) Cake, wood and grass

Answer: (a) Grass, flowers and leather
(c) Fruit peels, cake and lime juice
(d) Cake, wood and grass

Above all are the groups that contain only biodegradable items. Since plastic is not a biodegradable substance, that group cannot be considered as a biodegradable.

Question 2: Which of the following constitute a food-chain?

(a) Grass, wheat and mango
(b) Grass, goat and human
(c) Goat, cow and elephant
(d) Grass, fish and goat

Answer: (b) Grass, goat and human

Question 3: Which of the following are environment-friendly practices?

(a) Carrying cloth-bags to put purchases in while shopping
(b) Switching off unnecessary lights and fans
(c) Walking to school instead of getting your mother to drop on her scooter
(d) All of the above

Answer: (d) All of the above

Question 4: What will happen if we kill all the organisms in one trophic level?

Answer: If we kill all the organisms in one trophic level, the food supply to the next level will strop resulting in imbalance of the ecosystem. As a result animals in the higher levels will die making the growth of animals in the lower trophic level increase in an enormous way. All of this will affect the overall balance in the ecosystem.

Question 5: Will the impact of removing all the organisms in a trophic level be different for different trophic levels? Can the organisms of any trophic level be removed without causing any damage to the ecosystem?

Answer: Yes, the impact of removing all organisms in a trophic level will be different for different trophic levels. If all the producers are killed, it will cause death or migration of the primary consumers in the ecosystem. In the absence of producers, subsequent level of consumers will also be affected. But if primary consumers are removed, organisms of higher trophic level will die, while those of lower level (producers) show exponential growth much beyond the carrying capacity of the environment. Removal of the organisms in a trophic level will upset the whole ecosystem as all categories of organisms are linked through food chain. The survival of organisms of one trophic level depends on the existence of the members of other trophic level.

Question 6: What is biological magnification? Will the levels of this magnification be different at different levels of the ecosystem?

Answer: Biological magnification: The increase in concentration of harmful chemical substances like pesticides in the body of living organisms at each trophic level of a food chain is called biological magnification.
Yes, levels of bio-magnification would increase as the trophic level increases and would be the highest for topmost trophic level. It would affect their biological process such as growth, reproduction, etc.

Question 7: What are the problems caused by the non-biodegradable wastes that we generate?

Answer: Following are the problems caused by the non-biodegradable wastes:

  • These substances cannot be decomposed by the microorganisms.
  • As the quantity increases, dumping becomes a problem.
  • Non-biodegradable wastes like heavy metals may enter the food chain in the upper trophic levels.
  • They may escape to the groundwater which causes soil infertility and disturbance in pH of the soil.

Question 8: If all the waste we generate is biodegradable, will this have no impact on the environment?

Answer: Biodegradable wastes are decomposed by microorganisms into simpler substances themselves and provide raw materials for producers, but they also have adverse effects on the environment:

  • Slow decomposition of biodegradable waste will result in the release of foul smell and harmful gases. When inhaled by human beings, they may cause irritation, nausea, giddiness, etc.
  • Decomposing waste provides breeding ground for some harmful organisms. Abundance of harmful microorganisms may cause diseases in animals, plants and human beings.
  • Increase in the number of microorganisms in aquatic medium will- cause oxygen deficiency in waterbodies.

Question 9: Why is damage to the ozone layer a cause for concern? What steps are being taken to limit this damage?

Answer: Ozone layer is a protective shield around the earth. It prevents harmful ultraviolet radiation of the sun from reaching the earth. Air pollutants, like chlorofluorocarbons (CFCs), are causing depletion of ozone layer. This is allowing greater amount of UV radiation to reach the earth. UV radiation can upset the ecosystem by affecting photosynthesis in plants, destroying planktons and decomposers. In human beings, UV radiation may cause skin cancer, cataract of eyes and damage to immune system. Several developed as well as developing nations of the world have agreed to sign and obey the directions of TINEP (United Nations Environment Programme) to freeze the production of CFCs or to 1imit their production to some extent.

Topics covered under Class 10 Science Chapter 15 Our Environment

Below we have listed the topics discussed in NCERT Solutions for Class 10 Science Chapter 15. The list gives you a quick look at the different topics and subtopics of this chapter.

Section in NCERT BookTopics Discussed
15.1Ecosystem – What are its Components?
15.1.1Food Chains and Webs
15.2How Do Our Activities Affect the Environment?

NCERT Solutions for Class 10 Science Chapter 15 – A Brief Discussion

Chapter Overview: In this chapter, we shall be studying how various components in the environment interact with each other and how we impact the environment. This chapter explains our ecosystem, food chains and web. Further, it explains how our activities effect the environment.