Total number of meiotic division required for forming 100 zygotes/100 grains of wheat is

Options

A. 100
B. 75
C. 125
D. 50

Explanation

To determine the total number of meiotic divisions required for forming 100 zygotes (or 100 grains of wheat), we need to analyze the formation of male and female gametes in wheat.

### Step-by-Step Solution:

1. **Understanding Zygote Formation**:
- A zygote is formed by the fusion of male and female gametes. Therefore, to form 100 zygotes, we need 100 male gametes and 100 female gametes.

2. **Male Gamete Formation**:
- Male gametes are produced from microspore mother cells (MMC), which are diploid (2N).
- Each MMC undergoes meiosis to produce 4 microspores.
- Each microspore develops into a pollen grain, which contains two cells: a generative cell and a vegetative cell.
- The generative cell produces two sperm cells. Therefore, from one meiotic division, we can produce 4 microspores, which will ultimately lead to 4 sperm cells.

3. **Calculating Meiotic Divisions for Male Gametes**:
- To produce 100 sperm cells, we need to calculate how many meiotic divisions are necessary:
- Since 1 meiotic division produces 4 microspores (and thus 4 sperm cells), we need:
\[ \text{Number of meiotic divisions} = \frac{100 \text{ sperm}}{4 \text{ sperm per meiotic division}} = 25 \text{ meiotic divisions} \]

4. **Female Gamete Formation**:
- Female gametes are produced from megaspore mother cells (MMC), which are also diploid (2N).
- Each MMC undergoes meiosis to produce 4 megaspores, but only 1 of these megaspores survives and develops into an egg, while the other 3 degenerate.

5. **Calculating Meiotic Divisions for Female Gametes**:
- To produce 100 eggs, we need:
- Since 1 meiotic division produces 1 functional megaspore (egg), we need:
\[ \text{Number of meiotic divisions} = 100 \text{ meiotic divisions} \]

6. **Total Meiotic Divisions**:
- Now, we add the meiotic divisions required for male and female gamete formation:
\[ \text{Total meiotic divisions} = 25 \text{ (for male)} + 100 \text{ (for female)} = 125 \text{ meiotic divisions} \]

### Conclusion:
The total number of meiotic divisions required for forming 100 zygotes (or 100 grains of wheat) is **125**.