If diploid chromosome number in a flowering plant is 12, then which one of the following will have only 6 chromosomes

Options

A. Endosperm
B. Leaf cells
C. Cotyledons
D. Synergids

Explanation

To solve the question regarding the diploid chromosome number in a flowering plant being 12 and identifying which structure has only 6 chromosomes, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Diploid and Haploid Relationship**:
- In flowering plants, the diploid (2n) chromosome number represents the total number of chromosomes in somatic cells. If the diploid number is 12, then the haploid (n) number, which is found in gametes, is half of that.
- Calculation: \( n = \frac{2n}{2} = \frac{12}{2} = 6 \).

2. **Identify the Structures Mentioned**:
- The question mentions several structures: Androsperm, cotyledons, leaf cells, and synergids. We need to determine the chromosome number for each of these structures.

3. **Analyze Each Structure**:
- **Androsperm**: Formed when a male gamete (n) fuses with the central cell (2n), resulting in a triploid (3n) structure. Since 3n = 18, this is incorrect.
- **Cotyledons**: These are part of the seed and develop from the androsperm. Since androsperm is 3n, cotyledons will also have 3n = 18 chromosomes. This is incorrect.
- **Leaf Cells**: Leaf cells are somatic cells and will also have the diploid number, which is 2n = 12. This is incorrect.
- **Synergids**: These are cells in the embryo sac and are haploid (n). Since we calculated n = 6, this is correct.

4. **Conclusion**:
- The structure that has only 6 chromosomes is the **synergids**, as they are haploid and correspond to the haploid number derived from the diploid chromosome count of the flowering plant.

### Final Answer:
The structure that will have only 6 chromosomes is **synergids**.

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