$ABO$ 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?

Blood group $‘B'$ will have alleles

A person meets with an accident and great loss of blood has occurred. There is no time to analyse his blood group. It is safe to transfer blood of group

In a marriage between male with blood group $A$ and female with blood group $B$, the progeny had either blood group $AB$ or $B$. What could be the possible genotype of parents ?

The plasma membrane of the red blood cells has ...$A$... polymers that protrude from its surface and the kind of sugar is controlled by the gene. The gene I has three alleles ...$B$... The alleles and produce a slightly different form of the sugars, while allele i doesn't produce any ...$C$...

Choose the correct option for $A, B$ and $C$

When dominant and recessive alleles express themselves together, it is called