The haploid cell which divides by mitosis to form embryosac is

Options

A. megaspore mother cell
B. microspore mother cell
C. functional megaspore
D. non-functional megaspore

Answer

To solve the question "The haploid cell which divides by mitosis to form the embryo sac is," we need to analyze the options provided and understand the process of embryo sac formation in flowering plants.

### Step-by-Step Solution:

1. **Understanding the Terms**:
- **Haploid Cell**: A cell that contains one complete set of chromosomes (n).
- **Embryo Sac**: The female gametophyte in flowering plants, which develops from a megaspore.

2. **Identifying the Options**:
- **Megaspore Mother Cell**: This is a diploid cell (2n) that undergoes meiosis to produce megaspores.
- **Microspore Mother Cell**: This is also a diploid cell (2n) that undergoes meiosis to produce microspores (pollen grains).
- **Functional Megaspore**: This is a haploid cell (n) that develops from the megaspores produced by the megaspore mother cell and divides mitotically to form the embryo sac.
- **Non-Functional Megaspore**: These are the megaspores that do not develop further and degenerate.

3. **Analyzing the Megaspore Formation**:
- The megaspore mother cell undergoes meiosis to produce four haploid megaspores. Out of these, typically, three megaspores degenerate, and one survives to become the functional megaspore.

4. **Mitosis of the Functional Megaspore**:
- The functional megaspore undergoes mitotic divisions to form the embryo sac. This is the key step in the formation of the embryo sac.

5. **Conclusion**:
- Based on the analysis, the haploid cell that divides by mitosis to form the embryo sac is the **Functional Megaspore**.

### Final Answer:
The haploid cell which divides by mitosis to form the embryo sac is the **Functional Megaspore**.

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