Question

Assertion
In pigeons, females are heterogametic and males are homogametic.
Reason
In pigeons, females have ZW sex chromosomes and males have ZZ sex chromosomes.
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

In birds, the sex determination is done by ZZ-ZW type where females have ZW sex chromosomes and males have ZZ sex chromosomes.

Complete answer:
There are different types of sex determination techniques for humans and for birds, XX-XY type of determination is in humans where females have XX chromosomes and males have XY chromosomes. ZZ-ZW type of determination is in birds where males are homogametic i.e., they have ZZ chromosomes and females are heterogametic i.e., they have ZW chromosomes. It means that in humans, sex of the offspring depends on the type of male sex chromosome and in birds, sex of the offspring depends on the type of female sex chromosomes.
Assertion is correct as in birds i.e., in pigeons, females are heterogametic and males are homogametic and this is due to the reason that females have ZW (heterogametic) sex chromosomes and males have ZZ (homogametic) sex chromosomes which means the reason is all correct and it is correct explanation for the assertion given in the question.
If we look at options now:

Option A is Both Assertion and Reason are correct and Reason is the correct explanation for Assertion. Since both assertion and reason are correct and also reason is the correct explanation for the assertion, it is a correct option.
Option B is Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion. It is incorrect as reason is the correct explanation for assertion.
Option C is Assertion is correct but Reason is incorrect. This option is incorrect as both assertion and reason are correct.
Option D is Both Assertion and Reason are incorrect. This option is also incorrect as both assertion and reason are correct.

Hence, the correct answer is option (A).

Note: Since the assertion: In pigeons, females are heterogametic and males are homogametic is correct and the reason for this assertion is that in pigeons, females have ZW sex chromosomes and males have ZZ sex chromosomes. Thus, both the assertion and reason are correct and reason is also the correct explanation for this assertion.