In human blood types rh positive is a trait that shows simple dominance over rh negative. A woman has blood type A positive has a daughter who is type O positive and son who is Type B negative. Which of the following phenotypes is possible for the father?

OB negative

Explanation:

The mother is OA positive and she has a daughter that is OO positive, that means that one O and the rh positive, because of its dominance, were inherited from the mother, the other O was inherited from her father. The son is rh negative, if the mother is positive, the one with the negative rh type is the father, their son also has OB blood type, what means that he inherit the B type from his father.

The possible phenotypes for the father are B negative or B positive.

Explanation:

First, let's answer the ABO system.

The question informs us that the Mother is Type A and that she has a Type O daughter. This means that the Mother's genotype is A / O because the daughter must have at least one Type O allele inherited from the mother and one from the father.

The question also tells us that they have a son with a type B phenotype. We already know that one of the father's alleles is O, and necessarily the other allele must be B, so the father's genotype is B / O.

In relation to the Rh system, the couple's son is negative. Which means that he must inherit a recessive allele from his mother and one from his father. We know that the mother is Positive, so her genotype must be R / r. The father can be either Positive R / r or Negative r / r.

So the possible phenotypes for the father are B negative or B positive.