Question

If a child has blood type AB, he or she could NOT have been produced by which set of parents?

A. type B mother and type AB father

B. type A mother and type B father

C. type AB mother and type O father

D. type O mother and type O father

E. type O mother and type AB father

Answer 1

Answer:

Option C, D, E

Explanation: Blood group is determined by the presence of a group of antigens present on the surface of RBCs. The most widely spread blood group is the ABO blood grouping system and its father was Karl Landsteiner.

The blood group within an individual is determined by the combination of the antigens from either set of the parents. Half of the antigens get contributed by the male (father) gamete whereas the remaining half remains contributed by the female (mother) gamete.

So for an individual to express AB blood group; the criteria Is that they have a co dominance of the blood group antigens A and B which has to be contributed by their parents; half from the mother and remaining half from the father.

Condition of option C (Mother: AB and Father: O blood group)

Mother has two antigens within the gametes that is A and B. Whereas since the father is having a blood group of O; which means there are no alleles for the A and the B antigen and their combination cannot have a possibility of AB in their progenies due to no contribution of Aor B allele by the father

Condition of option D (Mother: O and Father: O blood group)

Since in this case, both the parents have blood group O; which means that none of them have A and B antigens on their RBCs. Thus the combination of their gametes cannot have an AB combination in any of their child

Condition of option E (Mother: O and Father: AB blood group)

In this case, mother has a blood group of A; which means there are no A and B antigens; whereas father has A and B both antigens on the surface of their RBCs. However a combination of the gametes cannot yield AB combination in their progenies as 50% gets contributed by the female parent and on account of the absence of A and B antigens, the AB probability will not be there in their progenies.