Question

Three sets of parents in the hospital had babies whose blood types are given.
Parents Children
Mr. & Mrs. White BABY 1
Type B and O Type A
Mr. & Mrs. Black BABY 2
Type AB and O Type B
Mr. & Mrs. Brown BABY 3
Type A and B Type O

BABY 4
Type AB
Which of the following offsprings are produced by the parents with phenotype Black?

• A. Baby 1
• B. Baby 2
• C. Baby 4
• D. Babies 1 and 2
• E. Any of the babies

Answer 1

The correct option is D Babies 1 and 2

The Browns have AB and O blood group with genotype AB (I${}^A$ I${}^B$) and O (ii). Presence of both I${}^A$ and I${}^B$ allele makes it possible for them to have Baby 1 (I${}^A$ I${}^A$) or (I${}^A$i) and Baby 2 (I${}^B$ I${}^B$) or (I${}^B$i). To have a child with O blood group (Baby 3), both parents should have at least one copy of "i" allele; the condition not fulfilled by The Browns. Likewise, to have a child with AB blood group one parent should have at least one (I${}^A$) allele and the other should have at least one (I${}^B$) allele. The Browns can't have Baby 3 and Baby 4. Thus, the correct answer is option D.