Morgan carried out several cross in Drosophila to study genes that were

Options

A. sex-linked
B. autosomal
C. involved in sex determination
D. segerated independently

Answer

### Step-by-Step Solution:

1. **Introduction to Morgan's Experiments**:
- Thomas Hunt Morgan conducted experiments on Drosophila (fruit flies) to study the inheritance patterns of certain traits, specifically focusing on eye color.

2. **First Cross**:
- Morgan crossed a red-eyed female Drosophila with a white-eyed male.
- The F1 generation consisted of red-eyed females and red-eyed males.
- In the F2 generation, he observed a ratio of red-eyed to white-eyed flies, confirming the inheritance pattern.

3. **Second Cross**:
- The second cross involved a red-eyed female (hybrid) crossed with a white-eyed male.
- The resulting progeny included red-eyed females, white-eyed females, red-eyed males, and white-eyed males.
- The ratio observed was 1:1:1:1, indicating a test cross scenario.

4. **Third Cross (Reciprocal Cross)**:
- In this cross, a white-eyed female was crossed with a red-eyed male.
- The progeny consisted of red-eyed females and white-eyed males.
- This cross demonstrated a different inheritance pattern than expected, reinforcing the idea of sex-linked traits.

5. **Conclusion**:
- Based on the results of these crosses, Morgan concluded that the gene responsible for eye color in Drosophila is sex-linked and located on the X chromosome.
- This means that the inheritance of the eye color gene does not follow Mendelian independent assortment but rather shows criss-cross inheritance.

6. **Final Answer**:
- Therefore, Morgan carried out several crosses in Drosophila to study genes that were sex-linked.