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Fertilization is
Fission of sperm and ova
Fusion of sperm and ova
Zygote formation
Gamete formation
Solution
Fusion of sperm and ova $Fertilization$ The process of fusion of a sperm (male gamete) with an ovum (female gamete) is called fertilization $Steps$ $(i)$ During coitus, semen is released by the penis into the vagina (insemination)$(ii)$ The motile sperms swim rapidly through the cervix, enter into the uterus and reach the ampullary isthmic junction of the oviduct (site of fertilization)$(iii)$ $A $ sperm comes in contact with the zona pellucida layer of the ovum and induces changes in the membrane to block the entry of additional sperms$(iv)$ The enzymes of the acrosome of sperm help to dissolve zona pellucida and plasma membrane of the ovum and sperm head is allowed to enter into the cytoplasm of the ovum, $i.e.,$ secondary oocyte$(v)$ Ultimately diploid zygote is produced by the fusion of a sperm and an ovum