Our Environment

2026Very short answer·2 marks·Q11Food chains and food webs

Explain why food chains generally consist of three or four steps.

2026Assertion-Reason·1 mark·Q9Food chains and food webs

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.

1. (a) Both Assertion
2. (b) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
3. (c) Both Assertion
4. (d) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
5. (e) Assertion
6. (f) is true, but Reason (R) is false.
7. (g) Assertion
8. (h) is false, but Reason (R) is true.

2026MCQ·1 mark·Q3Managing the garbage we produce

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?

1. (a) (i), (ii), (iii)
2. (b) (iv)
3. (c) (i) and (iii)
4. (d) (ii) and (iv)

2025MCQ·1 mark·Q15Food chains and food webs

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

1. (a) (i) and (iv)
2. (b) (i) and (iii)
3. (c) (ii) and (iii)
4. (d) (ii) and (iv)

2025MCQ·1 mark·Q16Food chains and food webs

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

1. (a) 1%
2. (b) 10%
3. (c) 90%
4. (d) 99%

2025Assertion-Reason·1 mark·Q20The ozone layer and how it is being depleted

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:

1. (a) Both A and R are true and R is the correct explanation of A.
2. (b) Both A and R are true, but R is not the correct explanation of A.
3. (c) A is true, but R is false.
4. (d) A is false, but R is true.

2025Very short answer·2 marks·Q26Managing the garbage we produce

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

2024MCQ·1 mark·Q15Food chains and food webs

Identify the food chain in which the organisms of the second trophic level are missing:

1. (a) Grass, goat, lion
2. (b) Zooplankton, Phytoplankton, small fish, large fish
3. (c) Tiger, grass, snake, frog
4. (d) Grasshopper, grass, snake, frog, eagle

2024Assertion-Reason·1 mark·Q18Food chains and food webs

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:

1. (a) Both A and R are true and R is the correct explanation of A.
2. (b) Both A and R are true, but R is not the correct explanation of A.
3. (c) A is true, but R is false.
4. (d) A is false, but R is true.

2024Short answer·3 marks·Q33(a)Food chains and food webs

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.

2024Short answer·3 marks·Q33(b)The ozone layer and how it is being depleted

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?

2023Short answer·3 marks·Q33(a)Ecosystem and its components

(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.

2023Very short answer·2 marks·Q26Food chains and food webs

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

2023Short answer·3 marks·Q33(b)Food chains and food webs

(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.

2022Very short answer·2 marks·Q7(b)Ecosystem and its components

(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.

2022Short answer·3 marks·Q13Food chains and food webs

(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.

2022Very short answer·2 marks·Q7(a)The ozone layer and how it is being depleted

What is ozone? How is it formed in the upper layers of the Earth's atmosphere? How does ozone affect our ecosystem?