How many haploid nuclei are present in a mature pollen grain

Options

A. One
B. Two
C. Three
D. Four.

Answer

### Step-by-Step Solution:

1. **Understanding Pollen Grain Development**:
- Pollen grains originate from pollen mother cells (PMCs), which are diploid (2N).

2. **Meiosis Process**:
- The pollen mother cells undergo meiosis, resulting in the formation of four haploid microspores from one diploid PMC.

3. **Functional Microspore**:
- Out of the four microspores produced, typically only one microspore is functional and develops into a mature pollen grain.

4. **Structure of Mature Pollen Grain**:
- A mature pollen grain consists of two types of cells:
- **Vegetative Cell**: This is the larger cell.
- **Generative Cell**: This is the smaller cell.

5. **Formation of Male Nuclei**:
- The generative cell undergoes mitosis, resulting in the formation of two male nuclei. These nuclei are haploid (N).

6. **Final Count of Haploid Nuclei**:
- Therefore, a mature pollen grain contains a total of **two haploid nuclei**.

### Conclusion:
- The answer to the question is that a mature pollen grain has **2 haploid nuclei**.