Question

The color blindness gene is recessive and X linked. It is written as Xb. A woman who is color blind has a son with a man with normal vision. What is the genotype of the son?

Answer 1

Answer:

XbY

Explanation:

The gene responsible for colorblindness is written as Xb since it is present on the X chromosome. In humans, sons get their X chromosomes from the mother while inheriting the Y chromosome from the father. In the given cross, the genotype of the colorblind mother would be XbXb (the X-linked recessive traits such as colorblindness are expressed in homozygous conditions in females).

She would transmit one copy of "Xb" to her son. The genotype of the father would be "XY" and he will give "Y chromosome" to the son. Therefore, the genotype of the son would be "XbY".