Sex-linked problem?

In humans, the condition for normal vision dominates color blindness; both alleles are linked to the X chromosome. A color-blind male marries a color-blind female. If they have a daughter, what is the chance she will have normal vision?

Sex-linked problem?
100%. If normal vision dominates, then the female would have to be homozygous recessive. A color blind male would have only one X chromosome which would also be recessive for the trait (since he is color blind). Therefore, the female would give a recessive x and the male would give a recessive x chromosome, and the daughter would be color blind.
Reply:The daughter woudl have a 0% chance of having normal vision. Since women are XX chromosome and men are XY chromosome, and both are color-blind they have the cc (C= dominate c=recessive) ,or homozygous recessive, on their X chromosomes, and cc*cc=cc 100% of the time. So no matter what, any child, male or female of theirs, will be color-blind since color-blindness is recessive and normal vision is dominant.
Reply:Your teacher wants you to answer:


0%





That's true if the parents have the same type of colorblindness. However, if they have different colorblindness, e.g. pop has red-green colorblindness while mom has yellow-blue colorblindness, then the daughter would have normal vision! LOL. So, correctly, we don't have enough information from this question to answer.