Question

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.

• 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.

Answer 1

The Correct Option is B

Step 1: Understanding the Assertion (A):
The assertion states that the accumulation of harmful chemicals is maximum in the organisms at the highest trophic level of a food chain. This is true due to a process called biomagnification. As harmful chemicals (like pesticides or pollutants) enter the food chain, they accumulate in the bodies of organisms. At each trophic level, the concentration of these chemicals increases because organisms at higher trophic levels consume a larger number of organisms from lower trophic levels, leading to a greater accumulation of the chemicals.

Step 2: Understanding the Reason (R):
The reason states that harmful chemicals are sprayed on crops to protect them from diseases and pests. This is also true. Pesticides and chemicals are commonly used in agriculture to protect crops from pests, diseases, and weeds. However, this reason alone does not explain why the accumulation of harmful chemicals is maximum in organisms at the highest trophic level of the food chain.

Step 3: Analyzing the Correctness of the Answer:
- Assertion (A) is true: The assertion is correct because harmful chemicals do indeed accumulate in higher trophic levels due to biomagnification.
- Reason (R) is true: The reason is also true because harmful chemicals are sprayed on crops to protect them from pests, but this spraying is just one source of harmful chemicals in the food chain.
- Reason (R) does not explain Assertion (A): While the spraying of harmful chemicals on crops is correct, it does not directly explain why the accumulation of these chemicals is maximum in the highest trophic level of the food chain. The explanation lies in the concept of biomagnification, which involves the increase in concentration of chemicals as they move up trophic levels, rather than just the spraying of chemicals on crops.

Conclusion:
The correct answer is: Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).