Question

Assertion: Cockroach shows sexual dimorphism
Reason: The female cockroach bears a pair of short threadlike anal styles
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
C. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect

Answer 1

Hint:-Sexual dimorphism is when there exists a systematic distinguishable feature between individuals of the same species but are of the opposite sex. This difference is beyond the difference in sexual organs in the two sexes. For example, in some groups like mammals, females are smaller when compared to males.

Complete Answer:-
Sexual dimorphism is one of the many consequences of natural selection and evolution. Given that natural selection occurs based on survival of the fittest, over time, organisms needed to develop necessary adaptations to keep up with the environmental changes as well as the reproductive competition between the same species. Therefore, for the sake of their reproductive success, they underwent adaptations which sometimes even put them in the disadvantage of being recognised easily by their predator. This is because reproductive succession which is the key to the survival of their species is more pivotal than the survival of the individuals.

Thus, the reason for the sexual dimorphism in cockroaches is to attract and access the opposite gender which eliminates options A and D. The dimorphism is that males have a pair of thread-like anal styles while the females lack such features. This eliminates options in which “Reason is correct” is present – options A and B.

Thus the correct answer is option C, Assertion is correct but Reason is incorrect

Note:- Example of phenomena for organisms underwent changes that made them vulnerable to predator attack is the colourations birds. The males are brightly coloured while the females are coloured in a way that they can camouflage in the environment which increases their chances of survival.