Q. ABO blood grouping is controlled by gene I which has three alleles and show co-dominance. There are six genotypes. How many phenotypes in all are possible?
A) Six
B) Three
C) Four
D) Five
Explanation
[Solution from source] The three alleles Iᴬ, Iᴮ and i give six genotypes, but Iᴬ and Iᴮ are dominant over i and co-dominant with each other, so only four phenotypes appear: A, B, AB and O. Six would be correct only if every genotype looked different. Answer (3).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.