question_answer

Though each pollen grain has two male gametes, atleast 10 pollen grains and not 5 pollen grains are required to fertilise 10 ovules present in particular carpel. Explain.

Answer:

A pollen tube carrying two male gametes, enters in an ovule and releases two male gametes which fuse with two different structures in the embryo sac, namely the egg and two polar nuclei. Hence, for fertilising 10 ovules, 10 pollen grains are required and not 5 pollen grains.