$A$ pair of contrasting characters is termed as

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

Define/Explain: Multiple Allelism.

In a family,the father has blood group '$A$' and the mother has blood group '$B$'. If the probability of their offspring having blood group '$AB$' is $50\%$,this indicates that:

If one parent has blood group $A$ and the other parent has blood group $B$,what blood groups can the offspring have?

On which chromosome are the genes for the $ABO$ blood group located?