[Sexual Reproduction in Flowering Plants :
Life History of Angiospermic Plants]
Answers
Explanation:
Microspores develop into pollen grains, which are the male gametophytes, while megaspores form an ovule that contains the female gametophytes.
In the ovule, the megasporocyte undergoes meiosis, generating four megaspores; three small and one large; only the large megaspore survives and produces the female gametophyte (embryo sac).
When the pollen grain reaches the stigma, it extends its pollen tube to enter the ovule and deposits two sperm cells in the embryo sac.
The two available sperm cells allow for double fertilization to occur, which results in a diploid zygote (the future embryo) and a triploid cell (the future endosperm), which acts as a food store.
Some species are hermaphroditic (stamens and pistils are contained on a single flower), some species are monoecious (stamens and pistils occur on separate flowers, but the same plant), and some are dioecious (staminate and pistillate flowers occur on separate plants).