Question

First husband of Asha had blood type A and their child had type O. She remarried. Second husband had blood group B and their child blood group AB. What is the genotype of Asha’s genotype and blood group is __________________________?
A. $ii$; Blood type O
B. ${{I}^{B}}i$; Blood type B
C. ${{I}^{A}}{{I}^{B}}$; Blood type AB
D. ${{I}^{A}}i$; Blood type A

Answer 1

There are four blood groups: A, B, AB and O. Each of them contains different antigens such as proteins or carbohydrates on the membrane of the red blood cells. Depending on the absence or presence of these antigens, as well as the presence of some specific antibodies in the blood plasma, it is possible to determine the blood groups we blood belong to.

Complete answer:
First marriage:
Blood group of child: O with genotype $ii$
We know that, child inherits alleles, from both the parents. Here, child has two $i$alleles. In this, one of them came from father, and another came from mother.
Then, blood group of husband: A with genotype ${{I}^{A}}i$
Hence, we can say that, mother and father had $i$allele.

Second marriage:
Blood group of child: AB with genotype${{I}^{A}}{{I}^{B}}$
Blood group of second husband: B
Here child has ${{I}^{A}}$ and ${{I}^{B}}$allele and husband has blood group B. Hence, he has allele${{I}^{B}}$.
Then, mother has ${{I}^{A}}$allele.
Therefore, the mother’s blood group is A with genome${{I}^{A}}i$.

Hence, the correct answer is option (D).

Additional information:
The blood types are determined genetically - each individual inherits it from their parents. Since, it is controlled by a single gene; a person has two alleles describing their blood group:
-Blood type A - AA or AO
-Blood type B - BB or BO
-Blood type AB - alleles AB
-Blood type O - alleles OO

Dominant alleles are A and B, and the allele O is recessive. It indicates that only people with OO alleles can have blood type O.

Note: The Rh factor is also inherited from our parents, but its inheritance does not depend on the ABO blood type alleles. There are 2 type alleles for the Rh factor called as Rh+ and Rh-.