Question

Give scientific reasons for the following statement:

Color blindness is a sex-linked recessive disorder.

Answer 1

Colour blindness:

1. Colour blindness is a type of disorder in which the person faces trouble in seeing or identifying certain colors like red, blue, and green.
2. They also have difficulties identifying the differences between color shades.

Colour blindness is a sex-linked recessive disorder:

1. Color blindness is caused by genes located on the X chromosome (sex chromosome).
2. It is a recessive disorder since it occurs when an individual has defects in all the X chromosomes of the cell.
3. Males have only one X chromosome and are hemizygous for X-linked traits. Therefore, defect in the single X chromosome can cause color blindness.
4. Females have two X chromosomes; hence they can be either homozygous or heterozygous.
5. If a female has defects in both sex chromosomes, they will develop color blindness.
6. However, if they have a defect in only one X chromosome, she will be a carrier.
7. Due to the above reasons, color blindness is called a sex-linked recessive disorder.