Which of the following events does not take place after the degeneration of the generative cell in pollen grain ?

Options

A. Entry of pollen tube inside the embryosac
B. Double Fertilization
C. Only triple fusion but not syngamy
D. Neither entry of pollen - tube inside the embryosac nor fertilization

Answer

To solve the question "Which of the following events does not take place after the degeneration of the generative cell in pollen grain?", we will analyze the options provided and understand the role of the generative cell in the pollen grain.

### Step-by-Step Solution:

1. **Understanding Pollen Grain Structure**:
- A mature pollen grain consists of two main cells: the vegetative cell and the generative cell.
- The vegetative cell is larger and responsible for developing the pollen tube.
- The generative cell is smaller and develops into two male gametes.

**Hint**: Remember the roles of the vegetative and generative cells in pollen grains.

2. **Degeneration of the Generative Cell**:
- If the generative cell degenerates, it means that it is no longer functional.
- Consequently, no male gametes can be produced since the generative cell is responsible for their formation.

**Hint**: Think about what happens when the generative cell is no longer present.

3. **Analyzing the Events**:
- **Entry of Pollen Tube Inside the Embryo Sac**: The pollen tube develops from the vegetative cell, so this event can still occur regardless of the status of the generative cell.
- **Double Fertilization**: This process requires two male gametes (one for syngamy with the egg and one for triple fusion with the polar nuclei). If the generative cell is degenerated, no male gametes are formed, thus double fertilization cannot occur.
- **Only Triple Fusion but not Syngamy**: This event also cannot occur because it requires one male gamete, which is not available if the generative cell is degenerated.
- **Neither Entry of Pollen Tube Inside the Embryo Sac nor Fertilization**: The entry of the pollen tube can still occur, so this option is incorrect.

**Hint**: Consider which events depend on the presence of male gametes.

4. **Conclusion**:
- The event that does not take place after the degeneration of the generative cell is **double fertilization** (option B). Since there are no male gametes produced, double fertilization cannot occur.

### Final Answer:
**Option B: Double fertilization will not occur.**