Question

The ratio of different genotypes to phenotypes for the ABO blood group system in the human population is

• A. 7: 4
• B. 4: 6
• C. 6: 4
• D. 4: 7

Answer 1

The correct option is C 6: 4

Multiple alleles $I^A$, $I^B$ and $I^O$ control the human ABO blood group system. The amount of different genotypes in multiple alleles can be calculated by the formula $\frac{n(n+1)}{2}$, where n is the number of alleles. Thus, for ABO blood groups in humans, the number of possible genotypes are $\frac{3(3+1)}{2}$ = 6.

The number of phenotypes of multiple alleles can be deduced by using the formula (n+1), where n is the number of alleles. Thus, for ABO blood groups, the number of phenotypes would be 3+1= 4.

Hence, the ratio of different genotypes to phenotypes is 6: 4.