A blood-type B woman is married to a man whose blood type is unknown.They have three children whose blood types are B, O, and AB.What is the husband's genotype?

Question

Quizplus · Accepted Answer

Since the mother is blood type B and she passed on a B allele to one of her children, we know she has genotype IBi. The child with blood type O must have received an i allele from the father, making his genotype ii. The child with blood type AB must have received an A allele from the father, but we don't know if he also received a B or i allele. Therefore, the husband's genotype must be IBi or iO. Choice B represents IBi and iO. Choice A and C represent genotypes with two B alleles, which is impossible since one of the children is type O. Choice D represents a genotype with two B alleles and a single parent contributing a B and an O allele, but we can't determine if the husband is the parent with the B or the O allele. Choice E represents a genotype with two O alleles, which is impossible since the mother has blood type B.

A Blood-Type B Woman Is Married to a Man Whose