Which of the following is correct about ZW - ZZ type of sex determination in birds?

Options

A. Males are heterogametic
B. Females are heterogametic
C. Females are homogametic
D. Both males and females are homogametic

Answer

To solve the question regarding ZW-ZZ type of sex determination in birds, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the ZW-ZZ System**: In birds, the sex determination system is based on the ZW-ZZ system. Males have two identical sex chromosomes (ZZ), while females have two different sex chromosomes (ZW).

2. **Identify the Genotypes**:
- Males: ZZ (homogamatic)
- Females: ZW (heterogamatic)

3. **Analyze the Options**:
- **Option 1**: Males are heterogamatic. This is incorrect because males have the ZZ genotype, which is homogamatic.
- **Option 2**: Females are heterogamatic. This is correct because females have the ZW genotype.
- **Option 3**: Females are homogamatic. This is incorrect since females are ZW, making them heterogamatic.
- **Option 4**: Both males and females are homogamatic. This is incorrect as only males are homogamatic (ZZ).

4. **Conclusion**: Based on the analysis, the correct statement about ZW-ZZ type of sex determination in birds is that females are heterogamatic.

### Final Answer:
**Option 2: Females are heterogamatic.**

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