CBSE Class 10 Science 2018 · Paper 31(B)/C · Question 19

Pollination: the transfer of pollen grains from the anther of a stamen to the stigma of a carpel (pistil). How it occurs: in self-pollination the pollen reaches the stigma of the same flower; in cross-pollination the pollen is carried from one flower to the stigma of another flower by agents such as wind, water, insects and birds. How pollination leads to fertilisation: a pollen grain that lands on a suitable stigma germinates, and a pollen tube grows out of it. The tube grows down through the style into the ovary and reaches an ovule, carrying the male germ cell. In the ovule the male germ cell fuses with the female germ cell (egg); this fusion is fertilisation and forms the zygote. The zygote develops into the embryo, the ovule into the seed and the ovary into the fruit.