Sometimes,there are more than two alleles for a given chromosome locus. In this case,a trait is said to be governed by:

$A$ child with a mother of $O$ blood group and a father of $A$ blood group will have which of the following blood groups?

$ABO$ blood groups in humans are controlled by the gene $I$. It has three alleles: $I^A, I^B$ and $i$. Since there are three different alleles, six different genotypes are possible. How many phenotypes can occur?

Define/Explain: Multiple Allelism.

In $ABO$ blood grouping,there are $P$ genotypes and $Q$ phenotypes.
$\quad P \quad\quad Q$

If the mother's blood group is '$A$' and the father's blood group is '$AB$',then the possible blood groups of their children will be: