Minimum number of meiotic divisions required to produce 100 wheat grains are

Options

A. 400
B. 25
C. 200
D. 20

Answer

To determine the minimum number of meiotic divisions required to produce 100 wheat grains, we need to consider the formation of male and female gametes through meiosis. Here’s a step-by-step breakdown of the solution:

### Step 1: Understand the Process of Meiosis
Meiosis is a type of cell division that reduces the chromosome number by half, resulting in the formation of gametes (sperm and egg cells). In wheat, which is a diploid organism (2n), meiosis occurs in the microspore mother cells (for male gametes) and megaspore mother cells (for female gametes).

### Step 2: Calculate Male Gametes
1. **Male Gamete Formation**: Each meiotic division in a microspore mother cell produces 4 microspores (male gametes).
2. **Required Male Gametes**: To produce 100 wheat grains, we need 100 male gametes.
3. **Meiotic Divisions for Male Gametes**: Since 1 meiotic division produces 4 microspores, to find the number of meiotic divisions needed for 100 male gametes, we calculate:
\[ \text{Number of meiotic divisions} = \frac{100 \text{ male gametes}}{4 \text{ microspores per meiosis}} = 25 \]

### Step 3: Calculate Female Gametes
1. **Female Gamete Formation**: Each meiotic division in a megaspore mother cell produces 4 megaspores, but only 1 of these becomes a functional female gamete (the other 3 are non-functional).
2. **Required Female Gametes**: To produce 100 wheat grains, we need 100 female gametes.
3. **Meiotic Divisions for Female Gametes**: Since only 1 functional megaspore is produced from each meiotic division, we need:
\[ \text{Number of meiotic divisions} = 100 \text{ female gametes} = 100 \]

### Step 4: Total Meiotic Divisions
Now, we can calculate the total number of meiotic divisions required:
\[ \text{Total meiotic divisions} = \text{Meiotic divisions for male gametes} + \text{Meiotic divisions for female gametes} = 25 + 100 = 125 \]

### Conclusion
The minimum number of meiotic divisions required to produce 100 wheat grains is **125**.