Alleles are

Determine the number of possible phenotypes in the $ABO$ blood grouping system.

In humans,the $ABO$ blood group is controlled by the $I$ gene. It has three alleles: $I^A$,$I^B$,and $i$. Although there are three different alleles,six different genotypes are possible. How many phenotypes are observed in this case?

$A$ couple has four children with blood groups $A, AB, A,$ and $O$ respectively. What are the genotypes of the parents' blood groups?

Explain Multiple Alleles and the concept of Dominance with an example.

In the $ABO$ blood grouping system,what are the number of possible phenotypes and genotypes,respectively?