Suppose that in Guinea pigs ABO blood types are determined like in humans,where I^A and I^B are expressed codominantly and i (blood type O)is recessive to both.During a set of routine crosses you notice something unusual: Repeated matings between a certain female with blood type AB and a certain male with blood type A produces F₁ Guinea pigs of all four blood types in the following ratios: 5A : 2B : 4AB : 1O.The genotypes of the parents are most likely: A)I^A/I^B for the female and I^A/I^A for the male. B)I^A/I^B for the female and I^A/i for the male. C)I^A/I^B/i for the female and I^A/I^A for the male. D)I^A/I^B/i for the female and I^A/i for the male. E)None of the answer options are correct.

Question

Quizplus · Accepted Answer

Given the offspring ratios and blood types, the female must carry both the A and B alleles (AB blood type) and also carry the i allele to produce offspring with blood type O. The male, having A blood type and producing offspring of all four blood types, must also carry the i allele. This scenario is only possible if the female is heterozygous for A and B alleles and also carries the i allele, and the male is heterozygous for the A allele and carries the i allele, which matches option D.

Suppose That in Guinea Pigs ABO Blood Types Are Determined