Which of the given statements is NOT CORRECT regarding colour blindness ?

Options

A. It is more common in mates than in females.
B. Homozygous recessive condition is required for the expression of colour blindness in females.
C. Males can be carriers of the trait.
D. Colour blind women always have a colourblind father and always produce a colour blind son.

Answer

To determine which statement is NOT CORRECT regarding color blindness, let's analyze each statement one by one.

1. **Statement 1**: "It is more common in males than in females."
- This statement is **correct**. Color blindness is indeed more prevalent in males due to its X-linked inheritance pattern. Males have one X and one Y chromosome (XY), while females have two X chromosomes (XX). If a male inherits the color blindness allele on his single X chromosome, he will express the trait, while a female would need to inherit the allele on both of her X chromosomes to express color blindness.

2. **Statement 2**: "Homozygous recessive condition is required for the expression of color blindness in females."
- This statement is also **correct**. For a female to express color blindness, she must be homozygous recessive, meaning both of her X chromosomes must carry the color blindness allele.

3. **Statement 3**: "Males can be carriers of a trait."
- This statement is **NOT CORRECT**. Males cannot be carriers of X-linked traits like color blindness because they have only one X chromosome. If they have the allele for color blindness on their X chromosome, they will express the trait. In contrast, females can be carriers if they have one normal allele and one allele for color blindness.

4. **Statement 4**: "A color blind woman always has a color blind father and always produces a color blind son."
- This statement is **correct**. A color blind woman must inherit the color blindness allele from her father (who must be color blind) and she can pass this allele to her sons, who will express the trait since they inherit their X chromosome from their mother.

Based on the analysis, the statement that is NOT CORRECT regarding color blindness is **Statement 3**: "Males can be carriers of a trait."