CBSE Class 10 Answered

Self-pollination by Mendel:

Pollen from the anthers drops on the stigma, a process that takes place as the flowers close for the night, and that sometimes occurs before they are completely developed and ready to open. The stigma at the top of the pistil is covered with a sticky substance that traps the pollen released by the anthers. From there, the sperm-bearing pollen travels down the pistil where it fertilizes the eggs.

Cross-pollination by Mendel:

Flowers of pure tall plants are emasculated, i.e. the stamens from the young flowers are removed with forceps and these are covered with polythene bags to avoid uncontrolled pollination. These flowers now have only pistil (female) part of the flower.

The flowers of the pure dwarf plant taken as male are also covered with polythene bags so that any undesired pollen may not fall on the stamens.

The stamens of flowers of the dwarf plant (taken as male) are plucked when the anthers are mature. The anthers are dusted upon the stigma of flowers of the tall plant taken as female and immediately covered with polythene bags to avoid any undesired pollen falling on stigma.

In order to obtain the F₁ generation, Mendel cross-pollinated the pea plants with contrasting characters.

In order to obtain the F₂ generation, Mendel self-pollinated the hybrids obtained in the F₁ generation.