What would be the sex of Drosophila with 3A+XXY genetic constitution?

Options

A. Male
B. Female
C. Meta female
D. inter sex

Answer

To determine the sex of Drosophila with a genetic constitution of 3A + XXY, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Genetic Makeup**:
- The genetic constitution is given as 3A + XXY. Here, "A" represents autosomes, and "X" and "Y" represent sex chromosomes.
- In Drosophila, the number of autosomes and sex chromosomes is crucial for determining the sex.

2. **Identify the Number of Autosomes**:
- The notation "3A" indicates that there are 3 pairs of autosomes (totaling 6 autosomes).

3. **Identify the Sex Chromosomes**:
- The notation "XXY" indicates that there are two X chromosomes and one Y chromosome.

4. **Calculate the Sex Ratio**:
- The sex determination in Drosophila is based on the ratio of the number of X chromosomes to the number of sets of autosomes.
- The formula used is:
\[ \text{Sex Ratio} = \frac{\text{Number of X chromosomes}}{\text{Number of sets of autosomes}} \]
- In this case, there are 2 X chromosomes and 3 sets of autosomes (since 3A means 3 pairs, which is 3 sets).
- Thus, the sex ratio is:
\[ \text{Sex Ratio} = \frac{2}{3} \]

5. **Determine the Sex Based on the Ratio**:
- According to C.B. Bridges' theory, the sex of Drosophila can be determined based on the ratio:
- A ratio of 1.0 or higher indicates a female.
- A ratio of 0.5 to 1.0 indicates a male.
- A ratio between 0.5 and 1.0 indicates intersex.
- Since our calculated ratio is \( \frac{2}{3} \) (approximately 0.67), it falls into the intersex category.

6. **Conclusion**:
- Therefore, the sex of Drosophila with the genetic constitution of 3A + XXY is intersex.

### Final Answer:
The sex of Drosophila with a genetic constitution of 3A + XXY is **intersex**.