Question

In a particular family, one parent has Type A blood, the other has Type B. They have four children. One has Type A, one has Type B, one has Type AB, and the last has Type O. What are the genotypes of all six people in this family?

NOTE: The ABO blood type gene has three alleles. IA and IB are codominant; i (for Type O) is recessive to both.

Answer 1

The correct answer is -

Parental genotypes: AO & BO

Children genotypes: AB, AO, BO, and OO

Step-by-step explanation:

In the human blood group system, more than two types of alleles are present that lead to the existence of four blood groups in the human population.

Here, A and B alleles are co-dominant while the O allele is recessive to both A and B alleles in the ABO system.

The cross depicting the genotypes of children is

IA IO

IB IAIB IBIO

IO IAIO IOIO

In this cross, we get the same result as given in the question -

One parent has A and the other has B type blood while the children have all four types of blood groups One has Type A, one has Type B, one has Type AB, and the last has Type O. It is possible only when parents are heterozygous in their genotypes and not expressing codominance.