The father's blood type is AB and the child's blood type is homozygous B.
Which of the following statements must be true about the mother of the child described above?

Question

Quizplus · Accepted Answer

The mother's blood type cannot be homozygous A. If the mother's blood type is homozygous A, the child's blood type can only be A or AB.
Key Takeaway: Blood type A and blood type B are co-dominant. If the mother's blood type is AB, she could potentially donate a B allele to the child. Likewise, if the mother's blood type is O, the child could still have blood type B if it receives the B allele from the father. The immune system will reject blood that does not match the blood of the recipient. If the mother's and child's blood posses different antigens, then they cannot serve as donors or recipients for each other.

The Father's Blood Type Is AB and the Child's Blood