Which type of sex determination mechanism is followed in birds?
a) Female XX and Male XO
b) Female ZW and Male ZZ
c) Female XY and Male XY
d) No Mechanism occur in birds

Options

A. Female XX and Male XO
B. Female ZW and Male ZZ
C. Female XY and Male XY
D. No Mechanism occurr in birds

Answer

To determine the type of sex determination mechanism followed in birds, we can analyze the options provided and the characteristics of sex determination in avian species.

### Step-by-Step Solution:

1. **Understanding Sex Determination in Birds**:
- In birds, the sex determination system is different from that in mammals. Birds exhibit a ZW sex determination system.
- In this system, females are heterogametic (ZW) and males are homogametic (ZZ).

2. **Analyzing the Options**:
- **Option a**: Female XX and Male XO - This is incorrect as it describes the sex determination mechanism found in grasshoppers, where females are homogametic (XX) and males are heterogametic (XO).
- **Option b**: Female ZW and Male ZZ - This is correct as it aligns with the known mechanism in birds where females have one Z and one W chromosome (ZW) and males have two Z chromosomes (ZZ).
- **Option c**: Female XY and Male XY - This is incorrect as it describes the sex determination mechanism in mammals, where both sexes have the same type of sex chromosomes (XX for females and XY for males).
- **Option d**: No Mechanism occurs in birds - This is also incorrect as birds do have a defined mechanism for sex determination.

3. **Conclusion**:
- The correct answer is **Option b: Female ZW and Male ZZ**.