Question

A man with blood group 'A' marries a woman with group 'B' blood. Their child has blood group 'O'. What are the genotypes of the parents?

• A. I^A i , I^B i
• B. I^A i , I^B I^B
• C. I^A I^A I^B I^B
• D. I^A I^B

Answer 1

Answer: (A)

Here, man with blood group A marries a woman with blood group B. The man may have either I^A I^A or I^Ai genotype. Similarly, the woman may have either I^B I^B or I^Bi genotype. If both of them are homozygotes, then all the progenies will have blood group AB (I^B I^B). If one of them is heterozygote then some children will have blood group AB(I^A I^B) and some will have either A group (Ai, if the blood group B parent is heterozygote having I^B i ) or B group (I^B i , if the blood group A parent is heterozygote having I^A i) but none of them will have blood group O. Blood group O of the progeny is possible only when both the parents are heterozygotes. Refer the cross given for detail. So, there is possibility of all the four types of blood groups B, A, B and O in their children.