Question

Even though each pollen grain has two male gametes, why are atleast 10 pollen grains and not 5 pollen grains required to fertilize 10 ovules

Answer 1

Hii..

Yes,pollen grains contain two male gametes but both are not involved in fertilising ovum
One is fused with egg cell and gets fertilised,while other male gamete fuses with the central cell to forms primary endosperm nucleus(PEN)

PEN ensures to give nutrition to devoloping embryo,hence to fertilize 10 ovules 10 pollen grains are required and not 5 pollen grains..

Hope it helps..!!