Color blindness is X-linked recessive and blood type is autosomal. If two parents who are both Type A and have normal vision produce a son who is color blind and type O, what is the probability that their next child will be a son who has normal vision and is blood type A

The information regarding the couples first son lets us deduce the genotypes for the parents. Since color blindness is X-linked recessive, the mother is a carrier of the color blindness gene, and since she has a normal vision, she has heterozygous genotype. As for blood type, both parents have the heterozygous 'AO' genotype.

There is a 1/2 chance that the child is a boy.

The possible outcomes for the child's blood type genotype are: AO, OA, AA, OO. Since A is dominant to O, there is a 3/4 chance that the child will have blood type A.

As for colorblindness, since the Y chromosome will be passed from the father, there is a 1/2 chance that the son will receIve the carrier X chromosome from the mother.

The probability of their next child being a son who has normal vision and is blood type A is:

[tex]P = \frac{1}{2}* \frac{3}{4}*\frac{1}{2}\\P=0.1875[/tex]