The sexual reproduction involves the fusion of two haploid cells (gametes) to form a diploid zygote.
Role of Meiosis: -
i) Meiosis help to reduce the number of chromosomes to one half in gametes.
ii) It also helps in exchange of genetic material by the process of crossing over.
Gametes: -
The gametes are of two types. Male gametes or sperms and Female gametes or eggs. Male gametes are formed in testes through the process of spermatogenesis. Female gametes are formed in ovaries through the process of oogenesis.
Fertilization: -
The two gametes from two parents, or from one parent (in case of self fertilization) unite together to form zygote which is the first diploid cell of the new generation.
New Individual: -
The diploid number of chromosomes in the zygote provides the genetic make up for the new individual. The zygote by simple mitosis changes into embryo, and the embryo develops into a new individual by cell division, differentiation and growth.