Which of the following males are not heterogametic ?

Options

A. Birds
B. Drosophila
C. Human
D. Grasshopper

Answer

To solve the question "Which of the following males are not heterogametic?", we need to understand the concept of heterogametic and homogametic individuals.

### Step-by-Step Solution:

1. **Define Heterogametic and Homogametic**:
- Heterogametic individuals produce two types of gametes due to having two different sex chromosomes (e.g., XY in males).
- Homogametic individuals produce only one type of gamete because they have two of the same sex chromosomes (e.g., XX in females).

2. **Analyze Each Option**:
- **A. Birds**: In birds, males have the sex chromosomes ZZ. They produce only one type of gamete (Z). Therefore, males in birds are not heterogametic; they are homogametic.
- **B. Drosophila**: In Drosophila (fruit flies), males have XY chromosomes. They produce two types of gametes (X and Y), making them heterogametic.
- **C. Humans**: In humans, males also have XY chromosomes and produce two types of gametes (X and Y), making them heterogametic.
- **D. Grasshoppers**: In grasshoppers, males are also heterogametic, having XY chromosomes.

3. **Conclusion**:
- The only males that are not heterogametic among the given options are those in **birds** (option A), as they are homogametic (ZZ).

### Final Answer:
The males that are not heterogametic are **A. Birds**.