Question

Which of the parents with following blood groups CANNOT have a child with blood group A?

• A. A and B (heterozygous)
• B. O and B
• C. AB and A (heterozygous)
• D. O and AB

Hint:

Blood group O never contributes A or B alleles.

Answer 1

The Correct Option is B

Step 1: Understanding ABO blood group inheritance.
Blood group A phenotype requires at least one A allele. Blood group O has genotype ii and cannot contribute an A allele.
Step 2: Analyzing option (B).
In O × B cross, possible offspring blood groups are B or O only, as neither parent contributes allele A.
Step 3: Conclusion.
Therefore, parents with blood groups O and B cannot have a child with blood group A.