Mark the correct option (w.r.t monosomy)

Options

A. Klinefelter's syndrome
B. Down's syndrome
C. Turner's syndrome
D. Haemophilia

Answer

### Step-by-Step Solution:

1. **Understanding Monosomy**:
- Monosomy refers to the condition where there is only one copy of a particular chromosome instead of the normal two copies (one from each parent). This is represented as 2n-1, where n is the haploid number of chromosomes.

2. **Causes of Monosomy**:
- Monosomy occurs due to the failure of chromosome segregation during gamete formation. This results in one gamete having one less chromosome. When this gamete fuses with a normal gamete, the resulting zygote will have one chromosome less than the normal diploid number.

3. **Identifying Syndromes**:
- **Klinefelter Syndrome (XXY)**: This condition has an extra copy of the X chromosome, making it a case of trisomy, not monosomy.
- **Down Syndrome (Trisomy 21)**: This syndrome involves an extra copy of chromosome 21, also a case of trisomy.
- **Turner Syndrome (X0)**: This condition is characterized by the presence of only one X chromosome in females instead of the normal two. This is a clear case of monosomy.

4. **Conclusion**:
- Among the options provided, the only condition that represents monosomy is Turner Syndrome. Therefore, the correct answer to the question regarding monosomy is Turner Syndrome.

### Final Answer:
The correct option with respect to monosomy is **Turner Syndrome** (Option 3).

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