Question

why does the zyhote begin to divide only after the division of primary endo sperm cells​

Answer 1

Embryo develops at the micropylar end of the embryo sac where zygote is situated. Most zygotes divide only after certain amount of endosperm is formed.

For its growth, zygote requires nourishment. It obtains the same from primary endosperm cell in which it is embedded. Therefore, growth, division and storage of food in primary endosperm cell or formation of endosperm is the pre requisite to growth and division of zygote.