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Class 10 Science Chapter 13: Our Environment Assertion-reason questions with answers

2 assertion-reason questions on Our Environment, each with its answer and the reason, written from the NCERT chapter. Open a question's solution to check your working; then take the free test to find your next chapter. Each question gives an Assertion (A) and a Reason (R); choose how they stand to each other.

Question 1
Assertion (A): A kingfisher in a pesticide-sprayed wetland carries a higher concentration of the pesticide than the small fish it eats. Reason (R): Non-degradable chemicals accumulate progressively at each trophic level.
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Answer: (a) Both A and R are true, and R is the correct explanation of A.

Both are true. The kingfisher is a level above the fish, and because the pesticide is not degraded it builds up at each level; R explains A.

Question 2
Assertion (A): Green plants are placed at the first trophic level of a food chain. Reason (R): Green plants in a terrestrial ecosystem capture about 1% of the sunlight falling on their leaves.
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Answer: (b) Both A and R are true, but R is not the correct explanation of A.

Both are true. Plants are at the first level because they make food from inorganic substances and make the Sun's energy available to consumers; the 1% figure is true but does not explain their position.

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