Question

If a child has O type of blood group and the father B type, the genotype of the father will be:

• A. $ii$
• B. $I^A{I}^B$
• C. $I^B$$i$
• D. $I^B{I}^B$

Answer 1

The correct option is C $I^B$$i$

ABO blood groups are controlled by three alleles $I^A,I^B$ and i.

$I^A$ and $I^B$ alleles are co-dominant to each other and are completely dominant over i allele.

The child has an O type of blood group.

This is produced by the homozygous recessive condition (i i).

If the father is of the B group, then he must have at least one recessive allele (i) to pass it on to his son.

The other ‘i’ allele in the son would have come from his mother.

Thus, the genotype of the father has to be $I^B$ $i$