Drosophila flies with XXY genotype are females, but human beings with such genotype are abnormal males. It shows that

Options

A. Y-chromosome is essential for sex determination in Drosophila
B. Y-chromosome is female determinating in Drosophila
C. Y-chromosome is male determining in human beings
D. Y-chromosome has no role in sex determination either in Drosophila or in human beings

Explanation

To solve the question regarding the XXY genotype in Drosophila and humans, we will analyze the options provided and the underlying principles of sex determination in both organisms.

### Step-by-Step Solution:

1. **Understanding the Genotype**:
- In Drosophila (fruit flies), the XXY genotype results in females. This indicates that the sex determination mechanism in Drosophila is not solely dependent on the presence of the Y chromosome.
- In humans, however, the XXY genotype (known as Klinefelter syndrome) results in abnormal males, indicating that the Y chromosome plays a crucial role in male determination.

2. **Analyzing the Options**:
- **Option 1**: "Bichromosome is essential for sex determination in Drosophila."
- This is incorrect because the Y chromosome does not determine sex in Drosophila; rather, it is the ratio of X chromosomes to autosomes that determines sex.

- **Option 2**: "Bichromosome is female determining in Drosophila."
- This is also incorrect. While the presence of two X chromosomes can lead to female development, the Y chromosome does not contribute to this determination.

- **Option 3**: "Y chromosome is male determining in human beings."
- This is correct. The presence of the Y chromosome in humans is a determining factor for male sex. If an egg is fertilized by a sperm carrying a Y chromosome, the resulting individual will typically develop as male.

- **Option 4**: "Y chromosome has no role in sex determination either in Drosophila or in human beings."
- This is incorrect, as the Y chromosome does play a significant role in male sex determination in humans.

3. **Conclusion**:
- Based on the analysis, the correct answer is **Option 3**: "Y chromosome is male determining in human beings."