The generative cell of a two celled pollen divides in the pollen tube, but not in a three-celled pollen. Give reasons.

Explanation

### Step-by-Step Solution:

1. **Understanding Pollen Structure**:
- Pollen grains can be classified as either two-celled or three-celled. In two-celled pollen, there are two cells: a generative cell and a vegetative (tube) cell. In three-celled pollen, there are three cells: one vegetative cell and two generative cells.

2. **Division of Generative Cell in Two-Celled Pollen**:
- In two-celled pollen, the generative cell has not undergone any division before the pollen tube formation. When the pollen grain germinates and forms a pollen tube, the generative cell divides within the pollen tube to produce two male gametes.

...