Question

The number of chromosomes in parents and offsprings of a particular species remains constant due to:

• A. Doubling of chromosomes after zygote formation
• B. Halving of chromosomes during gamete formation
• C. Doubling of chromosomes after gamete formation
• D. Halving of chromosomes after gamete formation

Answer 1

The correct option is B

Halving of chromosomes during gamete formation

The correct option is B.

Explanation of the correct option:

1. New offsprings are formed by the fusion of male and female gametes.
2. Gametes are formed by meiotic division.
3. Meiosis is a reduction division where the number of chromosomes gets halved.
4. Gametes formed are haploid in number(n).
5. When both gametes are fused, chromosome numbers get restored to diploid (2n).

Explanation of the incorrect options:

Option A:

The doubling of chromosomes after zygote formation would lead to tetraploidy in the zygote.

Option C:

1. The doubling of chromosomes after gamete formation would also lead to tetraploidy in the zygote.
2. The halving is to be done before gamete formation to restore the diploid state after fusion of the gametes.

Option D:

1. Halving of chromosomes after gamete formation would lead to a haploid state and result in a chromosomal deletion mutation.
2. Hence the number of chromosomes remains constant in parents and offsprings of a particular species.

Final answer: The number of chromosomes in parents and offsprings of a particular species remains constant due to the halving of chromosomes during gamete formation.