Answer:
here
Explanation:
a) Meiosis is required to provide genetic variation and to make sure that the number of chromosomes remain 46 in the zygote by producing haploid gametes.
b) Sperm cell's head contains the acrosome which has hydrolytic enzymes capable of dispersing the corona radiata (cell remnants from the follicle after ovulation) surrounding the ovum and penetrating the zona pellucida (glycoprotein coat surrounding the ovum's cell membrane).
The sperm's membrane then fuses with that of the ovum's, releasing its haploid nucleus inside the ovum, while its head, neck and tail remain on the outside.
The sperm's condensed nucleus expands and the female haploid nucleus undergoes meiosis-II before the nuclei fuse together to form the diploid zygote. This is fertilisation.
It is important to note that after the first sperm's penetration, the zona pellucida will modify its sperm receptors so that no other sperms can enter the ovum. It becomes impermeable.
c)
i) 16 cells (4^2)- if you don't remember the formula, you can draw it and count.
ii) It doesnt increase in size because the zona pellucida remains intact for a few days (5 to be specific) after fertilization.
