Select the correct option w.r.t. chromosome number in the life cycle of rice plant.

Options

A. `{:("Megaspore mother cell","Nucellus","Meiospore","Endosperm"),(24,24,24,36):}`
B. `{:("Megaspore mother cell","Nucellus","Meiospore","Endosperm"),(24,24,12,36):}`
C. `{:("Megaspore mother cell","Nucellus","Meiospore","Endosperm"),(12,24,12,"zero"):}`
D. `{:("Megaspore mother cell","Nucellus","Meiospore","Endosperm"),(24,24,24,24):}`

Answer

To solve the question regarding the chromosome number in the life cycle of the rice plant, we will analyze the different structures involved and their respective chromosome counts. Here’s a step-by-step breakdown:

### Step 1: Understand the Structures Involved
In the life cycle of the rice plant, we need to consider the following structures:
1. Megaspore Mother Cell (MMC)
2. Nucellus
3. Meiospores
4. Endosperm

### Step 2: Determine the Chromosome Number in Each Structure
1. **Megaspore Mother Cell (MMC)**:
- The MMC is diploid (2n). For rice, the total chromosome number is 24 (2n = 24).
- Therefore, the chromosome number in MMC = 24.

2. **Nucellus**:
- The nucellus is part of the ovule and contains the same chromosome number as the MMC.
- Therefore, the chromosome number in Nucellus = 24.

3. **Meiospores**:
- Meiospores are produced through meiosis from the MMC. Since meiosis halves the chromosome number, the number of chromosomes in meiospores will be half of that in the MMC.
- Therefore, the chromosome number in Meiospores = 24 / 2 = 12.

4. **Endosperm**:
- The endosperm is triploid (3n) and is formed after fertilization. It contains three sets of chromosomes, which is three times the number of the haploid (n) number.
- Therefore, the chromosome number in Endosperm = 3 * (24 / 2) = 36.

### Step 3: Summarize the Findings
- Megaspore Mother Cell (MMC) = 24
- Nucellus = 24
- Meiospores = 12
- Endosperm = 36

### Step 4: Identify the Correct Option
Now, we need to match these findings with the provided options. The correct chromosome numbers should be:
- MMC: 24
- Nucellus: 24
- Meiospores: 12
- Endosperm: 36

Among the options, the second option correctly lists these numbers as:
- 24 (MMC), 24 (Nucellus), 12 (Meiospores), 36 (Endosperm).

### Conclusion
The correct answer is **Option 2**.

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