Question

Draw a labelled diagram of the sectional view of a mature pollen grain in angiospenns. Explain the functions of its different parts.

Answer 1

The development of a mature pollen grain occurs as follows:

1. The microspore mother cell is diploid (2n).
2. It undergoes meiosis I followed by meiosis II.
3. As a result, a tetrad of four haploid microspores is formed.
4. The four microspores separate from one another.
5. Each microspore develops into a mature pollen grain.
6. The mature pollen grain has two wall layers:
   • Exine – outer thick protective wall
   • Intine – inner thin wall
7. Inside the mature pollen grain, there are:
   • Vegetative nucleus – controls the growth of the pollen tube.
   • Generative nucleus/cell – later divides to form two male gametes.

Microspore mother cell (2n) → Meiosis → Tetrad of haploid microspores → Separate microspores → Mature pollen grain.