CBSE Class 10 Science Chapter 13 Our Environment Important Questions 2027
Last updated:
25 questions from Our Environment appeared in 7 of the 7 CBSE papers we analysed (2022–2026) — here are the topics that matter, the questions that repeat, and every previous-year question from this chapter.
Key facts
- Natural Resources unit — 5 marks in the official syllabus
- Asked in 7 of 7 analysed papers (2022–2026)
- About 3.6 questions per paper (OR alternatives counted separately)
- 8 question patterns repeated across papers
Important topics in Our Environment
| # | Topic | Asked in | Importance |
|---|---|---|---|
| 1 | Food chains, food webs and trophic levels / 10% law | Board 2022Board 2023Board 2024Board 2025Board 2026Sample 2025Sample 2026 | ★★★★☆ |
| 2 | Ozone depletion and its effects | Board 2022Board 2024Board 2025Sample 2026 | ★☆☆☆☆ |
| 3 | Biodegradable vs non-biodegradable waste and its effects | Board 2025Board 2026Sample 2026 | ★☆☆☆☆ |
| 4 | Ecosystem components and flow of energy | Board 2022Board 2023Sample 2025 | ★☆☆☆☆ |
Repeated questions from Our Environment
1. Biomagnification up trophic levels
5×Board 2023Board 2024Board 2026Sample 2025Sample 20261/2 marks
The given cartoon addresses a growing concern (a farmer spraying pesticide on a cabbage farm, with the pesticide accumulating along a food chain up to fish). What impact will the process shown in the image have on Humans if they occupy the last trophic level? Explain.
2. Energy flow / 10% law
3×Board 2025Board 2026Sample 20251/2 marks
Explain why food chains generally consist of three or four steps.
3. Eco-friendly vs harmful human activity (MCQ)
2×Board 2026Sample 20261 marks
Given below are some of the statements regarding our environment: (i) Change in our life-styles have resulted in greater amounts of waste material generation. (ii) Changes in attitude have resulted in use of more disposable things. (iii) Changes in packaging has resulted in much of our waste becoming non-biodegradable. (iv) Organic farming. Which amongst these is not leading to any damage of environment? (A) (i), (ii), (iii) (B) (iv) (C) (i) and (iii) (D) (ii) and (iv)
4. Construct a food chain / food web
2×Board 2023Sample 20262/3 marks
About 100 acres of forest land was declared as Natural reserve park. The following organisms were predominant in the Natural reserve park: rabbit, frog, grass, fish, fox, water insects, zebra, peacock, snake, trees, bird, owl, insects, tiger, vulture, duck. Create a food web comprising two separate food chains with different producers by using the above data.
5. Effect of removing a trophic level
2×Board 2024Sample 20251/3 marks
Assertion (A): If the lions are removed from a food chain it will not affect the food chain, however if the plants are removed from a food chain it will disturb the ecosystem. Reason (R): Plants are producers who can make food using sunlight, while lions are consumers. [Options: A. Both A and R are true, and R is the correct explanation of A. B. Both A and R are true, and R is not the correct explanation of A. C. A is true but R is false. D. A is false but R is true]
6. Identify valid/invalid food chain (MCQ)
2×Board 2024Board 20251 marks
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 (A) (i) and (iv) (B) (i) and (iii) (C) (ii) and (iii) (D) (ii) and (iv)
7. Ozone: formation, function and depletion (descriptive)
2×Board 2022Board 20242/3 marks
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?
8. Natural vs artificial ecosystems and their maintenance
2×Board 2022Board 20232/3 marks
(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.
Our Environment questions by paper
| Paper | Questions | Marks |
|---|---|---|
| Board 2022 | 3 | 7 |
| Board 2023 | 3 | 8 |
| Board 2024 | 4 | 8 |
| Board 2025 | 4 | 5 |
| Sample 2025 | 4 | 5 |
| Board 2026 | 3 | 4 |
| Sample 2026 | 4 | 5 |
Counts include both options of internal-choice (OR) questions.
Previous year questions: Our Environment
Board 2026 3 questions
Given below are some of the statements regarding our environment: (i) Change in our life-styles have resulted in greater amounts of waste material generation. (ii) Changes in attitude have resulted in use of more disposable things. (iii) Changes in packaging has resulted in much of our waste becoming non-biodegradable. (iv) Organic farming. Which amongst these is not leading to any damage of environment? (A) (i), (ii), (iii) (B) (iv) (C) (i) and (iii) (D) (ii) and (iv)
Assertion (A): Highest percentage of pesticides is found in tertiary consumers in a food chain. Reason (R): Chemicals / pesticides get accumulated progressively at each trophic level. (A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A). (B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A). (C) Assertion (A) is true, but Reason (R) is false. (D) Assertion (A) is false, but Reason (R) is true.
Explain why food chains generally consist of three or four steps.
Sample 2026 4 questions
Which are the correct statements related to ozone? (i) Ozone layer helps in increasing the UV radiations reaching earth. (ii) Ozone is a deadly poison. (iii) Ozone layer shields the earth from UV radiations. (iv) Ozone layer prevents UV rays which cause skin cancer. (v) Ozone is formed with the help of Chloroflurocarbons. A. (i), (ii), (iii) B. (ii), (iii), (iv) C. (iii), (iv), (v) D. (i), (iv), (v)
Which of the following human activities has resulted in an increase of non-biodegradable substances? A. Organic farming B. Increase in tree plantation C. Use of plastic as packaging material D. Composting of kitchen waste
Assertion (A): Vulture will always have the least amount of pesticides in a food chain. Reason (R): Vulture occupies the last trophic level and it gets only 10% of energy of the previous trophic level. Options: A. Both A and R are true, and R is the correct explanation of A. B. Both A and R are true, and R is not the correct explanation of A. C. A is true but R is false. D. A is false but R is true.
About 100 acres of forest land was declared as Natural reserve park. The following organisms were predominant in the Natural reserve park: rabbit, frog, grass, fish, fox, water insects, zebra, peacock, snake, trees, bird, owl, insects, tiger, vulture, duck. Create a food web comprising two separate food chains with different producers by using the above data.
Board 2025 4 questions
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 (A) (i) and (iv) (B) (i) and (iii) (C) (ii) and (iii) (D) (ii) and (iv)
The percentage of solar energy which is not converted into food energy by the leaves of green plants in a terrestrial ecosystem is about : (A) 1% (B) 10% (C) 90% (D) 99%
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. Select the correct answer: (A) Both A and R are true and R is the correct explanation of A. (B) Both A and R are true, but R is not the correct explanation of A. (C) A is true, but R is false. (D) A is false, but R is true.
"Excessive use of chemicals and pesticides in agriculture adversely effect the environment." Justify this statement.
Sample 2025 4 questions
Identify the incorrect statement. 'The energy available to the producers is maximum' because: A. It is the first trophic level which absorbs 1% of light energy directly from the source. B. It utilizes the most of the chemical energy for its own respiration, growth, reproduction, movement etc. C. It utilizes 10% of light energy and transfers the rest to the next trophic level. D. It transfers only 10% of light energy to the next trophic level.
Which of the following is not a role of decomposers in the ecosystem? A. Natural replenishment of soil. B. Enrichment of oxygen in atmosphere. C. Waste decomposition. D. Break-down of dead remains.
Assertion (A): If the lions are removed from a food chain it will not affect the food chain, however if the plants are removed from a food chain it will disturb the ecosystem. Reason (R): Plants are producers who can make food using sunlight, while lions are consumers. [Options: A. Both A and R are true, and R is the correct explanation of A. B. Both A and R are true, and R is not the correct explanation of A. C. A is true but R is false. D. A is false but R is true]
The given cartoon addresses a growing concern (a farmer spraying pesticide on a cabbage farm, with the pesticide accumulating along a food chain up to fish). What impact will the process shown in the image have on Humans if they occupy the last trophic level? Explain.
Board 2024 4 questions
Identify the food chain in which the organisms of the second trophic level are missing: (a) Grass, goat, lion (b) Zooplankton, Phytoplankton, small fish, large fish (c) Tiger, grass, snake, frog (d) Grasshopper, grass, snake, frog, eagle
Assertion (A): Accumulation of harmful chemicals is maximum in the organisms at the highest trophic level of a food chain. Reason (R): Harmful chemicals are sprayed on the crops to protect them from diseases and pests. Select the correct answer from codes: (a) Both A and R are true and R is the correct explanation of A. (b) Both A and R are true, but R is not the correct explanation of A. (c) A is true, but R is false. (d) A is false, but R is true.
Plants -> Deer -> 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.
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?
Board 2023 3 questions
How do harmful chemicals get accumulated progressively at each trophic level in a food chain?
(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.
(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.
Board 2022 3 questions
What is ozone? How is it formed in the upper layers of the Earth's atmosphere? How does ozone affect our ecosystem?
(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.
(a) Name the group of organisms which form the first trophic level of all food chains. Why are they called so? (b) Why are human beings most adversely affected by bio-magnification? (c) State one ill-effect of the absence of decomposers from a natural ecosystem.
Frequently asked questions
What are the most important topics in CBSE Class 10 Science Chapter 13 Our Environment?
By how often and how recently they were asked: Food chains, food webs and trophic levels / 10% law; Ozone depletion and its effects; Biodegradable vs non-biodegradable waste and its effects.
How many marks does Our Environment carry in the CBSE Class 10 Science exam?
Our Environment is part of the Natural Resources unit, which carries 5 marks in the official syllabus. In the analysed papers it had about 3.6 questions per paper.
Do questions from Our Environment repeat in board exams?
Yes — 8 question patterns from this chapter appeared in two or more past board or official sample papers. They are listed on this page with the years they were asked.