Question

If a father has type A blood and the mother has Type AB blood, they would NOT have a child with which of the following blood types?
AB

A

B

O

Answer 1

Answer:

If a father has type A blood and the mother has type AB blood, they cannot have a child with blood type O, although depending on the father's genotype, they may not have children with a B blood type either.

Explanation:

Blood type is determined by the presence or absence of surface antigens A and B, which is genetically determined and establishes the pattern of inheritance.

Alleles that define the presence of antigens A and B are co-dominant, while the absence of antigens - as in blood type O - is a recessive trait.

• Type A contains antigen A and its genotype can be A|A or A|O.
• Type B contains the B antigen, whose genotype can be B|B or B|O.
• Blood type AB contains both antigens and a single genotypic expression A|B
• Type O blood lacks surface antigens, with genotype O|O.

The father with blood type A can have two genotypes, A|A or A|O, which raises 2 possible scenarios:

1. Father A|O with mother A|B

Alleles       A         O

A              A|A      A|O

B              A|B      B|O

In this case there is no chance of having a child with blood type O, 50% chance of having children with blood type A, 25% B and 25% AB.

2. Father A|A with mother A|B

Alleles        A        A

A               A|A     A|A

B               A|B     A|B

50% chance of having a child with blood type A and 50% with blood type AB. In this case there is no chance of having children with blood type O or B.