Answer:
Mitosis can be described as a type of cell division in which the daughter cells are exactly similar to the parent cell. On the other hand, as a result of meiosis, the daughter cells made have half the number of chromosomes as compared to the parent cell.
The egg cells and the sperm cells divide by meiosis instead of mitosis because when the egg cell and the sperm cell will unite, the resulting zygote will maintain the stable number of chromosomes. For example, the egg cell of the carp fish will have 52 chromosomes, the sperm cell will also have 52 chromosomes. When this egg cell and the sperm cell unite, then only a stable zygote with 104 chromosomes will be formed.
If the zygote had 104 chromosomes and the sperm had 104 chromosomes (if they divided by mitosis), then the resulting zygote would have 208 which will not be stable.