What is pollen grain

Options

A. Microspone mother cell
B. Male gamete
C. Male gametophyte
D. Partially developed embryo

Answer

### Step-by-Step Solution:

1. **Definition of Pollen Grain**:
- Pollen grain is a structure that is crucial for the reproduction of flowering plants. It is the male gametophyte that develops from microspores.

2. **Formation of Pollen Grain**:
- Pollen grains are formed from a microspore mother cell (also known as microsporocyte). This cell undergoes meiosis, a type of cell division that reduces the chromosome number by half.

3. **Meiosis Process**:
- During meiosis, the microspore mother cell divides to produce four haploid microspores. This arrangement of four microspores is referred to as a microspore tetrad.

4. **Maturation of Microspores**:
- Each microspore from the tetrad matures into a pollen grain. The pollen grain consists of two main parts: the vegetative cell and the generative cell.

5. **Cell Division in Pollen Grain**:
- The generative cell within the pollen grain will undergo further division to form two male gametes. Thus, the pollen grain ultimately contains one vegetative cell and two male gametes.

6. **Conclusion**:
- Therefore, pollen grain can be defined as the male gametophyte of flowering plants, which is responsible for the transfer of male genetic material during fertilization.

### Final Answer:
Pollen grain is the male gametophyte of flowering plants, formed from microspores and containing the male gametes.