Question

Mr. Arvind was born to parents with blood group O. If he marries a woman with the blood group AB, what are the chances of their offspring inheriting either A or B blood groups?

• A. 50%
• B. 25%
• C. 0%
• D. 75%

Answer 1

The correct option is A 50%

ABO blood groups of humans are controlled by three alleles $I^A,I^B$ and $i$

Out of the three alleles, $I^A$ and $I^B$ are completely dominant over $i$

The blood group O is a result of the homozygous recessive combination of $ii$

Both parents of Mr. Arvind possesses an O blood group.
Parents of Mr. Arvind: $ii$ X $ii$
Gametes: $i$ $i$
Hence, Arvind’s blood group is O ($ii$)

Mr. Arvind marries a woman with AB blood group $\left(I^A{I}^B\right)$

$\begin{array}{cc}& \text{i}\\ I^A& I^{A}i\left(A\right)\\ I^B& I^{B}i\text{(B)}\end{array}$

There are 50% chances of their offspring inheriting either A or B blood groups.