Question

(a) Describe any two devices in a flowering plant, which prevent both autogamy and geitonogamy.
(b) Explain the events up to double fertilisation after the pollen tube enters one of the synergids in an ovule of an angiosperm.

Answer 1

Double fertilization

Explanation:

(a) In a few flowering plants, male and female flowers are borne on various plants that mean a blossom is either male or female. This condition is known as Dioecy. It prevents both autogamy and geitonogamy. Case of dioecious plant – papaya. In a couple of flowering plants, the development of the stamens and carpels in a swinger flower isn't synchronized.This condition is known as Dichogamy. example of dichogamous plants – Cotton and Ficus.

b) After reaching the synergids, male gametes are released into the cytoplasm. One of the male gametes fuses with egg and the other fuses with polar nuclei leading to endosperm nucleus called triple fusion.