Question

Why does the number of chromosomes differ in ovum and zygote

Answer 1

When you talk about gametes they bear a haploid set of chromosomes and thus are a product of meiosis as ovum is ,  but the zygote is the product of syngamy (fertilisation) and undergoes mitosis.

Answer 2

Chromosomes numbers are different in ovum and zygote

Explanation:

• People have two of each chromosome, one from the mother and one from the father.
• The ovum is the unfertilized egg, so it only has the chromosomes from the mother (and each chromosome it has only once).
• The sperm is what carries the chromosomes (but only one of each chromosome) that come from the father.
• When they come together, the resulting cell has one of each chromosome, one from the mother and from the father.
• The resulting cell(s) also called a zygote, has twice the amount of chromosome than an ovum or a sperm.