Question

(a) Explain post pollination events leading to seed production in angiosperms
(b) List the different types of pollination depending on the source of pollen grain [5]

Answer 1

a) The post pollination events which leads to seed production in angiosperms are as follows:
i) After pollination, pollen-pistil interaction will take place, as a result of which germination of the pollen tube occurs which will transfer the two male gametes to the embryo sac.
ii) Then double fertilization will occur in which one male gamete fuses with the egg cell (syngamy), while the other fuses with two polar nuclei to form primary endosperm nucleus (PEN).
iii) The zygote then develops into an embryo while the PEN develops to form endosperm.
iv) The integuments get hard and form the seed coat while the ovule is converted into the seed. [2.5]

b) The different types of pollination depending on the source of pollen grains are as follows:
i) Autogamy : In this type of pollination, transfer of pollen grains occurs from the anther to the stigma of the same flower.
ii) Geitonogamy : In this type of pollination, transfer of pollen grains occurs from the anther to the stigma of another flower of the same plant.
iii) Xenogamy : In this type of pollination, transfer of pollen grains occurs from the anther to the stigma of a different plant. [2.5]