Which of the following statements is incorrect regarding sex determination in animals?

Options

A. Grasshoppers , male = autosomes + XO, female - autosomes +XX
B. Drosophila, males = autosomes + XY, female = autosomes +XX
C. Birds , females = autosomes + ZW, males = autosomes + ZZ
D. Insects (XO type), all sperms = one set of autosomes + X

Answer

To determine which statement is incorrect regarding sex determination in animals, we need to analyze the provided statements about different organisms and their sex determination mechanisms.

### Step-by-Step Solution:

1. **Understand the Concept of Sex Determination**:
- Sex determination in animals is primarily governed by sex chromosomes (also known as allosomes). These chromosomes can be either homologous (same) or heterologous (different).

2. **Identify Types of Heterogamy**:
- **Male Heterogamy**: Males have two different sex chromosomes (e.g., XY in humans). Here, males determine the sex of the offspring.
- **Female Heterogamy**: Females have two different sex chromosomes (e.g., ZW in birds). Here, females determine the sex of the offspring.

3. **Examine Each Statement**:
- **Statement 1**: In grasshoppers, the sex determination is based on the XX/XY system (XX is female, XO is male). This is correct.
- **Statement 2**: In Drosophila, the sex determination is based on the XX/XY system (XX is female, XY is male). This is also correct.
- **Statement 3**: In birds, the sex determination is based on the ZZ/ZW system (ZZ is male, ZW is female). This statement is correct as well.
- **Statement 4**: It states that all sperm in grasshoppers will have one set of autosomes plus one X chromosome. This is incorrect because, in grasshoppers, 50% of the sperm will have one set of autosomes and one X chromosome (XO), while the other 50% will have one set of autosomes and no sex chromosome (O).

4. **Conclusion**:
- The incorrect statement regarding sex determination in animals is **Statement 4**.

### Final Answer:
The incorrect statement regarding sex determination in animals is **Statement 4**.