Which of the following is incorrect regarding ZW-ZZ type of sex determination ?

Options

A. It occurs in birds and some reptiles
B. Females are homogametic and males are heterogametic
C. `1:1` sex ratio is produced in the offsprings
D. all of these

Explanation

To determine which statement is incorrect regarding the ZW-ZZ type of sex determination, we will analyze the options provided step by step.

### Step-by-Step Solution:

1. **Understanding ZW-ZZ Sex Determination:**
- In ZW-ZZ sex determination, females are ZW (heterogametic) and males are ZZ (homogametic).
- This system is found in birds, some reptiles, and certain fish.

2. **Analyzing the Options:**
- **Option 1:** "It occurs only in birds and some reptiles."
- This statement is correct as ZW-ZZ sex determination is primarily observed in these groups.

- **Option 2:** "Females are homo-gametic and males are hetero-gametic."
- This statement is incorrect. In the ZW-ZZ system, females are heterogametic (ZW) and males are homogametic (ZZ). Therefore, this is the incorrect statement we are looking for.

- **Option 3:** "1:1 sex ratio produced in the offspring."
- This statement is correct. In a typical ZW-ZZ cross, the offspring will exhibit a 1:1 sex ratio (1 male: 1 female).

3. **Conclusion:**
- The incorrect statement regarding the ZW-ZZ type of sex determination is **Option 2**.

### Final Answer:
The incorrect statement regarding ZW-ZZ type of sex determination is: **Females are homo-gametic and males are hetero-gametic.** (Option 2)

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