Question

A man with AB-blood group marries a woman with a blood group O. What is the probability of having O blood group among the offspring?

• A. 1 out of 4
• B. 2 out of 4
• C. 3 out of 4
• D. No offspring will have O blood group

Hint:

An AB parent can never have an O child, and an O parent can never have an AB child.

Answer 1

The Correct Option is D

Step 1: Concept
Blood groups are determined by the $I^A$, $I^B$, and $i$ alleles. AB group has the genotype $I^A I^B$, and O group has the genotype $ii$.

Step 2: Analysis
When crossing $I^A I^B \times ii$, the possible offspring genotypes are $I^A i$ (Group A) and $I^B i$ (Group B).

Step 3: Calculation
Each child has a 50% chance of being Group A and a 50% chance of being Group B. To have Group O, the child would need the genotype $ii$ (one $i$ from each parent).

Step 4: Conclusion
Since the AB parent can only provide $I^A$ or $I^B$ alleles, and never an $i$ allele, it is impossible for any offspring to have O blood group. Final Answer: (D)