Question

Why is human ABO blood group gene considered a good example of multiple alleles?

Answer 1

A gene is represented by two alleles. But, for the blood group in humans, there are three alleles namely I^A, I^B and i governing the same character. Thus, it is an example of multiple allele.

Allele from Parent 1	Allele from Parent 2	Genotype of offspring	Blood type of offspring
I A	I A	I A I A	A
I A	I B	I A I B	AB
I A	i	I A i	A
I B	I A	I A I B	AB
I B	I B	I B I B	B
I B	i	I B i	B
i	i	i i	O