A gene for the MN blood group has codominant alleles M and N. If both children in a family are of blood type M, which of the following situations is possible?
A) each parent is either M or MN
B) each parent must be type M
C) both children are heterozygous for this gene
D) neither parent can have the N allele

Question

Quizplus · Accepted Answer

If both children are of blood type M, it means they have either MM or MN genotypes. For this to happen, each parent must have at least one M allele to pass on to the children. Therefore, each parent could be either M (homozygous MM) or MN (heterozygous), making option A correct.

A Gene for the MN Blood Group Has Codominant Alleles