In human blood types, Rh positive is a trait that shows simple dominance over Rh negative. The Rh phenotype is recorded by stating "positive" or "negative" after the individuals ABO blood type. A woman who has blood type A positive has a daughter who is type O positive and a son who is type B negative. Which of the following phenotypes is possible for the father?
A) A negative
B) O negative
C) B positive
D) AB negative

Question

Quizplus · Accepted Answer

The woman has blood type A positive and can provide either an A or O allele and a positive Rh factor. The daughter is O positive, indicating she received an O allele and a positive Rh factor from her parents. The son is B negative, indicating he received a B allele and a negative Rh factor. For the children to have O and B blood types, the father must provide the O allele to the daughter and the B allele to the son, as well as the positive Rh factor to the daughter and a negative Rh factor to the son. Therefore, the father must have the genotype to provide a B allele and both Rh+ and Rh- alleles, making B positive (C) the only possible phenotype.

In Human Blood Types, Rh Positive Is a Trait That