Which of the following males are not heterogametic ?

Options

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

Answer

To solve the question of which males are not heterogametic, we need to understand the definitions of heterogametic and homogametic males in different species.

### Step-by-Step Solution:

1. **Understanding Heterogametic and Homogametic:**
- Heterogametic males produce two types of gametes (sperms) that carry different sex chromosomes. For example, in humans, males have XY chromosomes, meaning they can produce sperm with either X or Y chromosomes.
- Homogametic males produce only one type of gamete that carries the same sex chromosome. For example, in some species, males may have two of the same sex chromosome (XX).

2. **Analyzing Human Males:**
- In humans, males are heterogametic because they have XY chromosomes. They can produce two types of gametes (X and Y).

3. **Analyzing Bird Males:**
- In birds, the males have ZZ chromosomes. This means they produce only one type of gamete (Z), making them homogametic.

4. **Analyzing Drosophila and Grasshopper Males:**
- In Drosophila (fruit flies) and grasshoppers, males are also heterogametic, as they have XY chromosomes and produce two types of gametes (X and Y).

5. **Conclusion:**
- Among the options provided, the males that are not heterogametic are the males of birds, as they produce only one type of gamete (Z).

### Final Answer:
The males that are not heterogametic are the males of birds.

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