Embryo sac develops from megaspore mother cell through

Options

A. two meiotic and two mitosis divisions
B. one meiotic and three mitosis divisions
C. two meitotic divisions
D. one meiosis and two mitotic divisions

Answer

To solve the question "Embryo sac develops from megaspore mother cell through," we need to analyze the processes involved in the development of the embryo sac from the megaspore mother cell. Here’s a step-by-step breakdown of the solution:

### Step 1: Understand the Terms
- **Embryo Sac**: This is the female gametophyte in angiosperms, which contains the egg cell and other cells necessary for fertilization.
- **Megaspore Mother Cell**: This is a diploid cell (2n) that undergoes meiosis to produce megaspores.

### Step 2: Identify the Process
- The development of the embryo sac starts with the megaspore mother cell undergoing meiosis. This process is called **megasporogenesis**.

### Step 3: Meiosis
- The megaspore mother cell undergoes **meiosis**, resulting in the formation of four haploid megaspores (n). Typically, three of these megaspores degenerate, leaving one functional megaspore.

### Step 4: Mitosis
- The remaining functional megaspore undergoes **three rounds of mitotic divisions**. This process is known as **megagametogenesis**.
- These divisions result in the formation of the embryo sac, which consists of:
- 1 egg cell
- 2 synergids
- 1 central cell (which contains two polar nuclei)
- 3 antipodal cells

### Step 5: Conclusion
- Therefore, the embryo sac develops from the megaspore mother cell through **1 meiotic division followed by 3 mitotic divisions**. This corresponds to option D: **1 meiosis and 2 mitotic divisions**.

### Final Answer
The correct option is **D: 1 meiosis and 2 mitotic divisions**.

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