Which one correctly determines the sex

Options

A. XO condition in lTurner's syndrome determines female sex
B. Homozygous XX produce male in Drosophila
C. Homozygous ZZ determine female sex in birds
D. XO determines male sex in Grasshopper.

Answer

To determine which option correctly identifies the mechanism of sex determination, let's analyze each option step by step.

### Step-by-Step Solution:

1. **Understanding Sex Determination in Humans**:
- In humans, sex is determined by the presence of X and Y chromosomes.
- Males have XY chromosomes (heterogametic), while females have XX chromosomes (homogametic).

**Hint**: Remember that males have one X and one Y chromosome, while females have two X chromosomes.

2. **Analyzing the First Option (XO condition and Turner syndrome)**:
- Turner syndrome occurs when there is a missing or incomplete X chromosome in females, typically represented as XO.
- However, the XO condition does not determine female sex; it indicates a female with a missing X chromosome.

**Hint**: Turner syndrome is characterized by the absence of one X chromosome, which does not support the claim of determining female sex.

3. **Analyzing the Second Option (Homozygous XX male in Drosophila)**:
- In Drosophila (fruit flies), sex is determined by the ratio of X chromosomes to autosomes.
- A normal male Drosophila has a ratio of 0.5 (one X chromosome to two sets of autosomes), but homozygous XX males do not exist.

**Hint**: The sex determination in Drosophila relies on the X-to-autosome ratio, not on homozygosity.

4. **Analyzing the Third Option (Homozygous ZZ determines female sex in birds)**:
- In birds, the sex determination system is ZW (females) and ZZ (males).
- ZZ represents males, while ZW represents females, making this option incorrect.

**Hint**: In birds, ZW indicates females, while ZZ indicates males.

5. **Analyzing the Fourth Option (XO determines male sex in grasshoppers)**:
- Grasshoppers utilize the XX/XO sex determination system.
- In this system, females are XX and males are XO, confirming that XO does indeed determine male sex.

**Hint**: In grasshoppers, the presence of a single X chromosome (XO) indicates a male.

### Conclusion:
The correct option is **Option 4: XO determines the male sex in the grasshopper**.