. Name the parts labelled as A, B, C and D in the diagram given below

Best Answer

(a)  A - Pollen grains

B  - Pollen tube

C-Ovary

D - Ovule (ovum)

(b) The transfer of pollen grains from anther (male sexual part) of a flower to the stigma part of the pistil (female sexual part) is known as pollination. Signification of pollination. It may be. the cause  of variation in a species of a plant.

(c) Fertilisation in flower. A pollen grain contains two male gametes. When a pollen grain falls on the stigma of the carpel, it grows a pollen tube downwards into the style. One of the male gametes reaches the ovary through pollen tube and fuses with female gamete present in the ovule. This fertilisation of the two germ cells forms a zygote. The zygote is capable of growing into a new plant.

The other male gamete fuses with two polar nuclei to form endosperm nucleus. This fusion is called triple fusion. The zygote grows into an embryo and an endosperm nucleus grows into endosperm (the food storage tissue of seed).

(i) All the eggs in the ovule  present  in the ovary  of a flower  gets fertilised  by male gametes from  pollen grains  and  grow  to become  seeds.

(ii)  The ovary of flower develops and becomes fruit