Draw a neatly lablled diagram to explain plant fertilization. Write few points on pollen grain. (AS5)

h) The pollen grain reaches the stigma of the flower called pollination.

i) The pollen tube starts germinating, the pollen contains 2 cells- generative cell and a vegetative cell.

j) Both the cells travel through the pollen tube which leads them to the embryo sac.

k) The embryo sac is a 7 celled 8 nuclei structure.

l) One of the male gametes fuses with the female egg- called syngamy, while the other fuses with the 2 polar nuclei forming a triploid- called triple fusion.

m) Since 2 kinds of fertilization take place in a plant, it is also called double fertilization.

n) After fertilization, the triploid central cell develops into endosperm while the zygote develops into an embryo.

Pollen grain:

a) Pollen grains are the structures or male gametophytes produced in the anthers of the flower which contain the mail gametes.

b) They are coarse powdery grain-like structure.

c) They have double walls with pores. The outer wall is made up of sporopollenin which is one of the hardest substance known.

d) Pollen grain travels from the anthers of the stamen to the stigma of the pistil through various agents to deliver the male gamete by the process called pollination.