question_answer

A normal woman whose father was colourblind, marries a normal man. What kinds of children can be expected and in what proportion?

A) All daughters normal, 50% of sons colourblind

B) All daughters normal, all sons colourblind

C) 50% daughters colourblind, all sons normal

D) All daughters colourblind, all sons normal

Correct Answer: A

Solution :

[a] A colourblind father (genotype \[({{X}^{c}}Y)\]) would produce carrier daughters (genotype \[X{{X}^{c}}\]). When a carrier female (\[X{{X}^{c}}\]) marriages a normal man (XY), the types of offspring produced would be all normal daughters and half of the sons (50%) would be colourblind and the remaining half would be normal. This pattern of inheritance can be explained by the following cross