CBSE Class 9 Answered

Sexual reproduction occurs when a male gamete and a female gamete fuse together. This fusion of gametes is called fertilisation. Fusion of the gametes allows some of the genetic information from each parent to mix and produce offspring that resemble their parents, but are not identical to them. This leads to variety in the offspring. In human beings, each gamete contains 23 chromosomes. When the male and female gametes fuse, they form a zygote, which in turn becomes a new embryo containing the full 46 chromosomes – half from the father and half from the mother.

We need to reproduce because reproduction is necessary to maintain the number of individuals of a species. It helps in the survival of the species and prevents their extinction. It also leads to the evolution of the species in the long run.