Male heterogamety is absent in

Options

A. birds
B. human
C. roundworm
D. Drosophila

Answer

### Step-by-Step Solution:

1. **Understand the Concept of Male Heterogamety:**
- Male heterogamety refers to the condition where males produce two different types of gametes. This is typically represented by the presence of two different sex chromosomes (e.g., XY in humans).

2. **Identify Examples of Male Heterogamety:**
- In species exhibiting male heterogamety, males produce two types of gametes: one carrying the X chromosome and the other carrying the Y chromosome. Examples include humans, brown worms, and fruit flies (Drosophila).

3. **Consider Other Organisms:**
- Now, we need to consider other groups of organisms to determine where male heterogamety is absent.

4. **Examine Birds:**
- In birds, the sex determination system is different. Birds exhibit female heterogamety, where females have two different sex chromosomes (ZW), while males have two of the same type (ZZ).

5. **Conclusion:**
- Since birds do not exhibit male heterogamety, the answer to the question is that male heterogamety is absent in birds.

### Final Answer:
- Male heterogamety is absent in **birds**.

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