Question

Assertion (A): In sexual reproduction, though the genetic material DNA (in the form of chromosomes) from two gametes, male and female gametes, combines together to form a new cell ‘zygote’ but the amount of DNA in ‘zygote’ does not get doubled.

Reason (R): The gametes are special type of cells called reproductive cells which contain only half the amount of DNA (or half the number of chromosomes) as compared to the normal body cells of an organism. So, when a male gamete combines with a female gamete during sexual reproduction, then the new cell ‘zygote’will have the normal amount of DNA (or normal number of chromosomes) in it.

पर्याय

• Both A and R are true and R is correct explanation of the assertion.

• Both A and R are true but R is not the correct explanation of the assertion.

• A is true but R is false.

• A is false but R is true.

Answer 1

Both A and R are true and R is correct explanation of the assertion.

Explanation:

During sexual reproduction, the male and female gametes each contain only half the normal amount of DNA (haploid number of chromosomes). When they fuse during fertilisation, the zygote receives the normal amount of DNA (diploid number of chromosomes), not double the amount. Therefore, Assertion (A) is true.

Since gametes have half the normal number of chromosomes, their fusion restores the normal chromosome number in the zygote. Therefore, Reason (R) is true and correctly explains Assertion (A).

Hence, both A and R are true, and R is the correct explanation of A.