Question

Assertion (A) : The population of melanized moths increased in areas after Industrial Revolution.
Reason (R) : In Industrial environment lichen covered trees were replaced by soot-covered trees offering better camouflage to dark coloured moths.

• 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.

Hint:

Industrial melanism proves that natural selection favors the variant that is best adapted to the current environment.
It is not that the moths "changed color" individually; rather, the existing dark variants survived better and reproduced more.

Answer 1

The Correct Option is A

The question involves understanding the relationship between the assertion and reason regarding the population dynamics of melanized moths during the Industrial Revolution. Let’s evaluate both the assertion and the reason step-by-step:

1. Assertion (A): The population of melanized moths increased in areas after the Industrial Revolution.
   • This statement refers to the well-known phenomenon of industrial melanism, particularly observed in the peppered moth (Biston betularia) during the Industrial Revolution in England.
   • Before the Industrial Revolution, light-colored lichen covered trees were common, providing camouflage for lighter-colored moths, protecting them from predators.
   • However, during the Industrial Revolution, the pollution caused by factories resulted in trees being covered with soot, favoring the survival of dark-colored (melanized) moths, which were better camouflaged against predators on the darkened tree bark.
   • Thus, the assertion is true as the population of melanized moths did indeed increase in polluted areas due to the change in environmental conditions.
2. Reason (R): In the Industrial environment, lichen-covered trees were replaced by soot-covered trees offering better camouflage to dark-colored moths.
   • This reason accurately describes the environmental changes that occurred during the Industrial Revolution.
   • The pollution led to a significant reduction in lichen on trees and an increase in soot deposition, which affected the camouflage and survival rates of moths.
   • This provides a valid explanation for why the population of melanized moths increased — because they were less visible to predators on soot-covered trees.
   • Therefore, the reason is true and correctly explains the assertion.

Conclusion: Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of the Assertion (A). The correct answer is: Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).