How many reduction divisions are necessary for the formation of 200 grains of wheat

Options

A. 250
B. 150
C. 200
D. 360

Explanation

To determine how many reduction divisions are necessary for the formation of 200 grains of wheat, we need to analyze the formation of both the egg cells and the pollen grains.

### Step-by-Step Solution:

1. **Understanding the Formation of Egg Cells:**
- In wheat, the formation of egg cells occurs through a process called meiosis (reduction division).
- A megasporangium (megaspore mother cell) undergoes meiosis to produce four megaspores (egg cells).
- Out of these four megaspores, three degenerate, leaving only one functional egg cell.
- Therefore, for every egg cell formed, one reduction division (meiosis) is needed.

2. **Calculating Reduction Divisions for Egg Cells:**
- Since we need 200 grains of wheat, we require 200 egg cells.
- Thus, the number of reduction divisions needed for egg cell formation = 200 (one division per egg cell).

3. **Understanding the Formation of Pollen Grains:**
- The formation of pollen grains also occurs through meiosis.
- A microspore mother cell undergoes meiosis to produce four pollen grains.
- Therefore, for every set of four pollen grains, one reduction division is needed.

4. **Calculating Reduction Divisions for Pollen Grains:**
- To find out how many reduction divisions are needed for 200 pollen grains, we can use the unitary method.
- If one reduction division produces 4 pollen grains, then to produce 200 pollen grains, we set up the following calculation:
\[ \text{Number of divisions} = \frac{200 \text{ pollen grains}}{4 \text{ pollen grains per division}} = 50 \text{ divisions} \]

5. **Total Reduction Divisions:**
- Now, we add the reduction divisions needed for both egg cells and pollen grains:
\[ \text{Total reduction divisions} = \text{Divisions for eggs} + \text{Divisions for pollen} = 200 + 50 = 250 \]

### Final Answer:
The total number of reduction divisions necessary for the formation of 200 grains of wheat is **250**.

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