Question

The blood group of a woman is 'O'. She has two brothers, one with 'A' group and the other with 'B' group. The genotypes of her parents are

• A. $I^A{I}^O$-$I^A{I}^B$
• B. $I^A{I}^O$-$I^B{I}^O$
• C. $I^A{I}^B$-$I^O{I}^O$
• D. $I^O{I}^O$-$I^A{I}^O$

Answer 1

Answer: (B)

$I^A{I}^O$-$I^B{I}^O$

A woman with O blood group has genotype $I^O{I}^O$ which means that both parents should have at least one $I^O$ allele. In order to have a child with B blood group, at least one parent should have one copy of $I^B$ allele. Parents with $I^A{I}^O$ and $I^B{I}^O$ will have children with $I^A{I}^O$ (A blood group), $I^B{I}^O$ (B blood group), $I^A{I}^B$ (AB blood group) and $I^O{I}^O$ (O blood group). Thus, the correct answer is option B.