Question

An allele contributed by one parent is ${I^A}$ and an allele contributed by the other parent is i, the blood group of offspring will be
A. A
B. AB
C. B
D. O

Answer 1

Hint: The surface of red blood cells possesses a special molecule, named antigen which is responsible for the classification of blood into four different groups. These blood groups are A, B, AB and O.The antigens that are found on the red blood cell surface are a type of glycoproteins.

Complete answer:
Chromosome 9 regulates the human ABO blood group. Three alleles named ${I^A}$, IB, and I are responsible for categorizing human blood. ${I^A}$ and ${I^B}$ are always dominant. ${I^A}$ and ${I^B}$ are codominant to each other.
The person who belongs to blood group A comprises the genotype ${I^A}$${I^A}$ or ${I^A}$i.
The person who belongs to blood group B comprises the genotype ${I^B}$${I^B}$ or ${I^B}$i.
O blood group possess genotype ii.
An AB blood group involves the genotype ${I^A}$${I^B}$.
Here we can see one allele contributed by a parent is ${I^A}$ and another parent contributes the allele I, which will provide the offspring with the blood group A. As the ${I^A}$ allele is dominant over i, The phenotypic expression of ${I^A}$ will be visible in offspring.

So, the correct answer is option

Note: Two types of antigens are found on the red blood cell surface. These are antigen A and antigen B. Antigen A is found in blood group A and antigen B is found in B blood group. AB blood possesses both the antigens A and B. O blood group does not contain any antigens.