Question

Colorblindness is an X-linked recessive trait. A couple has two sons: one with normal vision and the other is color-blind. Which of the following statements HAS to be TRUE?

The father is colorblind
The mother is colorblind
The father has normal color vision
The sons are not true siblings
None of the above

Answer 1

Option 3). The father has normal color vision.

Step-by-step explanation:

Being an X-linked recessive trait, color blindness is inherited from the X chromosome. In this instance, the couple has two sons: one who is color blind and the other who sees normally. Given that the mother passed on the colorblindness allele to her son, we can infer from this information that the mother is a carrier of the gene. However, since the father does not have the colorblindness allele, it can be assumed that he has normal color vision. As a result, it must be true that the father has normal color vision.