Describe microsporogenesis and the structure of a mature pollen grain, with a labelled diagram.

1. 1 · Define in one line. Microsporogenesis is the formation of microspores from a pollen mother cell by meiosis.
2. 2 · Explain the process.
   • Each sporogenous cell is a potential pollen mother cell (2n).
   • It divides by meiosis into a microspore tetrad of four haploid cells.
   • As the anther matures and dries, the microspores separate and develop into pollen grains.
3. 3 · Describe the pollen wall. Exine: hard, of sporopollenin, with germ pores. Intine: thin, of cellulose and pectin.
4. 4 · Describe the cells inside. A large vegetative cell with food and an irregular nucleus, and a small spindle-shaped generative cell. Over 60% of angiosperms shed pollen at this 2-celled stage.
5. 5 · Draw a mature pollen grain. [Diagram: exine, intine, germ pore, vegetative cell nucleus, generative cell]
6. 6 · Link to daily life. Sporopollenin lets pollen survive as fossils; pollen banks store pollen in liquid nitrogen for crop breeding.
7. 7 · Close in one line. So each pollen grain is a haploid male gametophyte, built to survive its journey to a stigma.

Scoring tip: Write that the pollen mother cell is diploid and the microspores are haploid. The word meiosis is a marking point.