Principles of Inheritance and Variation Question 27
27. If two persons with ’ $A B$ ’ blood group marry and have sufficiently large number of children these children could be classified as ’ $A$ ’ blood group: ’ $A B$ ’ blood group: ’ $B$ ’ blood group in $1: 2: 1$ ratio. Modern technique of protein electrophoresis reveals presence of both ’ $A$ ’ and ’ $B$ ’ type proteins in ’ $A B$ ’ blood group individuals. This is an example of :
(a) incomplete dominance
(b) Partial dominance
(c) Complete cominance
(d) Codominance
Show Answer
Answer : d
Hints & Solution
(d) ABO blood group system in human beings is an example of codominant, dominant recessive and multiple alleles. Blood groups are controlled by the gene I located on $9^{\text{th }}$ chromosome that has 3 multiple alleles, out of which any two are found in a person. In codominance, both genes express themselves completely.
