Select incorrect statements

Options

A. Male insects have one chromosome less than the female insects
B. In birds sex is determined by the female and not the male
C. In humans , sex is determined equally by the male and the female
D. none of these

Answer

To solve the question of selecting the incorrect statements regarding sex determination in various organisms, we will analyze each statement step by step.

### Step-by-Step Solution:

1. **Statement 1 Analysis**:
- The statement claims that male insects have one chromosome less than female insects.
- In insects, the sex determination system is often XX-XY or XX-XO.
- In the XO system, females are XX (two X chromosomes) and males are XO (one X chromosome).
- Therefore, this statement is **correct**.

2. **Statement 2 Analysis**:
- The statement claims that in birds, sex is determined by the female and not the male.
- Birds follow a ZW-ZZ sex determination system where females are ZW and males are ZZ.
- The female produces two types of gametes (Z and W), while males produce only Z gametes.
- The sex of the offspring is determined by the type of gamete the female contributes. Thus, this statement is also **correct**.

3. **Statement 3 Analysis**:
- The statement claims that in humans, sex is determined equally by the male and female.
- Humans have an XY sex determination system where males are XY and females are XX.
- Males produce two types of gametes (X and Y), while females produce only X gametes.
- The sex of the offspring is determined by whether the male's X or Y gamete fertilizes the female's X gamete. Therefore, this statement is **incorrect** because the male contributes the determining factor for the sex of the offspring.

4. **Conclusion**:
- The only incorrect statement is **Statement 3**.

### Final Answer:
- The incorrect statement is **Statement 3**: "In humans sex is determined equally by the male and the female."