Question

Very short answer type question:

Even though each pollen grain has 2 male gametes, why at least 20 pollen grains are required to fertilize 20 ovules in a particular carpel?

Answer 1

One of the pollen grain's male gametes fuses with the egg cell during double fertilisation, while the other male gamete fuses with the secondary nucleus. Thus, 20 pollen grains are required to fertilise 20 ovules in a specific carpel.