Question

Blood grouping in humans is controlled by

• A. 4 alleles in which I${}^A$ is dominant
• B. 3 alleles in which I${}^A$ and I${}^B$ are dominant
• C. 2 alleles in which none is dominant
• D. 3 alleles in which I${}^A$ is recessive
• E. 3 alleles in which I${}^A$ and I${}^B$ are codominant

Answer 1

The correct option is E 3 alleles in which I${}^A$ and I${}^B$ are codominant

Human blood group inheritance is the example of codominance and multiple alleles. It is governed by three alleles namely, I${}^A$, I${}^B$ and I${}^O$ which makes options A and C incorrect. I${}^A$ and I${}^B$ show codominance; thus option B is wrong and option E is correct. Allele I${}^O$ is recessive to both I${}^A$ and I${}^B$; option D is incorrect.

Thus, the correct answer is option E.