1. Isogamy - In this male & female gametes are similar.
2. Anisogamy - The male & female gametes are different.
1. Activation -
In this process cortex of egg activated & formed the fertilizine membrane over P.M.
Cytoplasm of ova initiate different metabolic activities, this activities essential for initiate cleavage.
2. Amphimixis -
In this process male & female pronuclei are fused and formed the diploid structure, i.e. zygote.
Genetic variation stimulate in the species.