Question

The number of nuclei present in a zygote is
(i) none. (ii) one. (iii) two. (iv) four

NCERT Class VIII
Science - Main Course Book

Chapter 9. Reproduction in Animals

Answer 1

Dear Student,

◆ Answer - (iii)

The number of nuclei present in a zygote is two.

● Explanation -

• Ovum (female gamete) and sperm (male gamete) are both haploid (n) entities.
• Zygote is formed by fertization. i.e. fusion of male and female gametes.
• Thus, in zygote male and female gametes combine together to form diploid (2n) zygote.

Ovum(n) + Sperm(n) => Zygote(2n)

Thanks dear. Hope this helps you...

Answer 2

The number of nuclei present in a zygote is one.

Answer - (Option (ii))

Explanation:

• A zygote is formed by the fusion of the sperm and ovum cells by the fertilization process and a single uni-nucleus is formed in the zygote.
• The haploid sperm and ovum cells combine to form 2n or diploid zygote cells.
• The diploid cells will have copies of the haploid parent cell’s chromosomes and DNA.
• The nuclei of the diploid cells again fuse to form a single nucleus.
• The zygote later undergoes "rapid cell division" to form the embryo.