Colorblindness is a recessive trait caused by an error on the X chromosome. XA=Normal Vision and Xa=Colorblind. If mom is normal (not a carrier) and dad is colorblind, what will be the resulting phenotype of the children? .

So the mother will have two X chromosomes (since she’s female) that are normal (since she is not a carrier), so her genotype will be XA and the gametes she is going to provide is only XA. For the dad, he will have an X chromosome carrying the colourblind gene, which is Xa, and a Y chromosome since he’s male. Referring to the picture, the daughter will receive an XA from mom and Xa from dad, while the son will get an XA from mom and Y from dad.