Why does the zygote begin to divide only after the division of Primary endosperm cell (PEC)?
The endosperm plays an important role in supplying food to the developing embryo. Once the division of PEC or Primary Endosperm Cell is complete, there is sufficient availability of food for the embryo.
In the absence of food, the zygote won’t be able to get the necessary raw materials for making new cells. Hence, the division of zygote beings only after the division of Primary Endosperm Cell (PEC).