Question

If two-person with 'AB' blood groups marry and have a sufficiently large number of children, these children could be classified as ‘A' blood groups. 'AB’ blood group 'B' blood group in a 1: 2: 1 ratio. The modern technique of protein electrophoresis reveals the presence of both 'A' and 'B' type proteins in 'AB' blood group individuals. This is an example of
A. Codominance
B. Incomplete dominance
C. Partial dominance
D. Complete dominance

Answer 1

Hint: The presence of two types of antigen in the blood is a deviation from the mendelian law of dominance and unlike the case where generally one allele is dominant over the other and gets expressed, in human AB blood type, both antigens are present.

Complete answer: A person with blood type AB is bound to have both the A and B alleles.
Codominance, in genetics, is a condition wherein two alleles (variants of a single gene) get expressed to an equal degree within an organism.
As a result of this, each allele expresses its trait in the organism at the same time.
The table given below shows the different types of blood found in human beings:

Therefore, the correct answer is option D. Incomplete dominance.

Note: ABO blood grouping in humans also is a classic example of the phenomenon of multiple allelism.