Red green colourblindness is a sex linked trait. Which of the given statements is not correct regarding colourblindness ?

Options

A. It is more common in males than in females
B. Homozygous recessive condition is required for the expression of colourblindness in females.
C. Males can be carriers of the trait
D. Colourblind women always have colourblind father and always produce colorblined son.

Explanation

To determine which statement regarding red-green color blindness is incorrect, let's analyze each statement step by step:

### Step 1: Understanding the Trait
Red-green color blindness is a sex-linked trait, specifically an X-linked recessive disorder. This means that the gene responsible for color blindness is located on the X chromosome.

### Step 2: Analyzing Each Statement

1. **Statement 1: It is more common in males than in females.**
- **Analysis:** This statement is correct. Males have one X chromosome (XY), so if they inherit the X chromosome with the color blindness allele (Xc), they will express the trait. Females have two X chromosomes (XX), so they need to inherit the color blindness allele on both X chromosomes (XcXc) to express the trait. Therefore, color blindness is indeed more common in males.

2. **Statement 2: Homozygous recessive condition is required for the expression of color blindness in females.**
- **Analysis:** This statement is also correct. For a female to express color blindness, she must have two copies of the recessive allele (XcXc). If she has only one copy (XcX), she will be a carrier but not express the trait.

3. **Statement 3: Males can be carriers of the trait.**
- **Analysis:** This statement is incorrect. Males cannot be carriers of X-linked traits because they have only one X chromosome. They either express the trait (if they have the Xc allele) or do not (if they have the normal allele, X). Therefore, they cannot be carriers like females who have two X chromosomes.

4. **Statement 4: A colorblind woman always has a colorblind father and always produces a colorblind son.**
- **Analysis:** This statement is correct. A colorblind woman (XcXc) must inherit one Xc from her father (who must be colorblind, XcY) and one Xc from her mother (who could be a carrier or colorblind). When she has children, her sons will inherit the Y chromosome from their father and one Xc from her, making them colorblind.

### Conclusion
The statement that is **not correct** is **Statement 3: Males can be carriers of the trait.**

### Final Answer
**The incorrect statement is: Males can be carriers of the trait.**

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