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.
