13Q What are the parental genotypes when one parent has AB blood type and the other B but among the children 25% are A, 25% are AB and 50% are B?
1. AB and BO
2. AB and BB
3. AB and OO
4. AA and BB
5. None of the above
CORRECT! The AB phenotype has to be an AB genotype. That leaves the remaining parent either BB or BO. If it were BB, then 50% of the children would be AB, not 25%. Thus, the remaining parent must be BO.