Question

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

(b) Work out a cross up to F₁ generation only, between a mother with blood group A (Homozygous) and the father with blood group B (Homozygous). Explain the pattern of inheritance exhibited.

Answer 1

(a) This is because more than two alleles govern the human ABO blood group gene. 

(b)

The cross exhibits co-dominance. When the two alleles I^A and I^B are present together, both the alleles express each other equally forming the blood group AB.