Question

two statements are given — one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below.
Assertion (A): Greater numbers of individuals are present in lower trophic levels of all food chains.
Reason (R): As the amount of energy decreases at each successive trophic level, larger numbers of individuals are required at the lower trophic levels to support higher/next trophic levels.

• 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 and Reason (R) is false.
• D. Assertion (A) is false and Reason (R) is true.

Answer 1

The Correct Option is A

Assertion (A) is true. In a typical food chain, the number of individuals at each trophic level decreases as you move up the chain. This is due to the energy pyramid in which energy is lost between trophic levels.

Reason (R) correctly explains this. A large number of producers (at the first trophic level) are required to support a smaller number of primary consumers. Similarly, a smaller number of primary consumers support an even smaller number of secondary consumers, and so on. The energy loss (about 90%) at each trophic level limits the number of individuals that can be supported at higher levels.