CBSE Class 10 Science 2017 · Paper 531/3 · Question 9

Pollination: the transfer of pollen grains from the anther of a stamen to the stigma of a carpel. Self-pollination and cross-pollination: (i) In self-pollination the pollen reaches the stigma of the same flower; in cross-pollination it is carried from one flower to another flower. (ii) Self-pollination usually needs no outside agent; cross-pollination needs an agent such as wind, water or animals. (iii) Self-pollination gives offspring with less variation; cross-pollination between flowers of different plants combines germ cells from two parents and gives more variation. Fruit without the flower's own stamens: the carpel of the flower is intact, so pollen from another flower reaches its stigma by cross-pollination (carried by wind, water or insects, or placed there by hand). A pollen tube grows through the style to the ovule, fertilisation takes place, and the ovary develops into the fruit while the ovules become seeds.