Question

A boy has the blood group O. What is true of the inheritance of this blood group in his case?

Options

• His mother should be with AB blood group

• Both his parents could be heterozygous A group

• His father could be homozygous B group

• His mother could be homozygous A group

Answer 1

Both his parents could be heterozygous A group

Explanation:

Blood group O means the genotype must be ii (homozygous recessive). For a child to have blood group O, they must inherit an i allele from each parent. Therefore, both parents must have at least one i allele, meaning they could be heterozygous A (IAi) or heterozygous B (IBi), but not blood group AB or homozygous A or B.