Question

A woman with blood group ‘AB’ marries a man with blood group “O”. Which of the following statements is true about the possibilities of inheritance of the blood groups?

• A. They produce children with blood group ‘O’ only.
• B. They produce children with blood group ‘AB’ only.
• C. They produce children some with blood group ‘AB’ and some with blood group ‘O’.
• D. They produce children some with blood group ‘A’ and some with blood group ‘B’.

Hint:

If one parent is 'O' and the other is 'AB', the children will {never} have the blood group of either parent. They will always be A or B.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
ABO blood grouping is an example of multiple allelism and codominance, determined by alleles $I^A, I^B,$ and $i$.
Step 2: Key Formula or Approach:
Woman (Group AB) Genotype: $I^A I^B$
Man (Group O) Genotype: $ii$
Cross: $I^A I^B \times ii$
Punnett Square:
\[ \begin{array}{|c|c|c|} \hline \text{Gametes} & i & i
\hline I^A & I^A i \text{ (Group A)} & I^A i \text{ (Group A)}
\hline I^B & I^B i \text{ (Group B)} & I^B i \text{ (Group B)}
\hline \end{array} \] Step 3: Detailed Explanation:
The mother provides either an $I^A$ allele or an $I^B$ allele.
The father provides only the $i$ allele.
Resulting offspring can only have genotypes $I^A i$ (Phenotype A) or $I^B i$ (Phenotype B).
There is a 0% probability of having a child with group AB or group O.
Step 4: Final Answer:
The children will have either blood group A or blood group B.