Can a child have blood group ‘O’ if his/her parents have blood group ‘A’ and ‘B’? Explain



The child with blood group O will have homozygous recessive alleles. Therefore, both the parents should be heterozygous, i.e. genotype of father will be ${{I}^{A}}$i or ${{I}^{B}}$ i and of mother will be ${{I}^{A}}$ i or ${{I}^{B}}$ i.
A child have blood group O in the following two cases:
Case I When father is ${{I}^{A}}$i and mother is ${{I}^{B}}$ i.

The offsprings will have the above possible blood groups, i.e. AB, A, B and O.
Case II When father is ${{I}^{B}}$ i and mother is ${{I}^{A}}$ i.