Question

Human blood type is determined by codominant alleles. There are three different alleles, known as ${{\text{I}}^{\text{A}}}$, ${{\text{I}}^{\text{B}}}$, and i. the ${{\text{I}}^{\text{A}}}$ and ${{\text{I}}^{\text{B}}}$, alleles are codominant, and the i allele is recessive.
The possible human phenotypes for blood group are type A, type B, type AB, and type O. type A and B individuals can be either homozygous ({{\text{I}}^{\text{A}}}$$$${{\text{I}}^{\text{A}}}or {{\text{I}}^{\text{B}}}$$$${{\text{I}}^{\text{B}}}, respectively), or heterozygous (${{\text{I}}^{\text{A}}}$i or ${{\text{I}}^{\text{B}}}$i, respectively).
A woman with type A blood and a man with type B blood could potentially have offspring with which of the following blood types?
A. Type A
B. Type B
C. Type AB
D. All of the above

Answer 1

The human blood grouping system, known as ABO blood grouping, is based upon the presence or absence of two antigens, namely A and B, which are present on the surface of RBCs. In response to these antigens, antibodies are also present in the plasma.

Complete answer:
There are four types of blood groups, A, B, AB, and O. Three major alleles for determining the blood groups are ${{\text{I}}^{\text{A}}}$, ${{\text{I}}^{\text{B}}}$, and i. The genotype of blood group A could be either {{\text{I}}^{\text{A}}}$$$${{\text{I}}^{\text{A}}} or ${{\text{I}}^{\text{A}}}$i and similarly, blood group B could have genotype either of {{\text{I}}^{\text{B}}}$$$${{\text{I}}^{\text{B}}} or ${{\text{I}}^{\text{B}}}$i. Blood group O is present if neither ${{\text{I}}^{\text{A}}}$nor ${{\text{I}}^{\text{B}}}$is present and in AB blood group both ${{\text{I}}^{\text{A}}}$ and ${{\text{I}}^{\text{B}}}$ are present. For blood group A, the antigen on the surface of RBC is A and the antibody would be anti-B. For blood group B, the antigen would be B and antibody, anti-A. For AB blood type, antigens on the surface of RBCs are both A and B and no antibody is present. For O blood type, there would be no antigen, but antibodies would be of both A and B types.

If a woman has a blood group of type A then it could be either in the form of homozygous alleles or heterozygous alleles, ${{\text{I}}^{\text{A}}}$ or ${{\text{I}}^{\text{A}}}$i, respectively. Similarly, if the man has a blood type of B then the alleles could be homozygous or heterozygous.

In the homozygous condition, ${{\text{I}}^{\text{A}}}$ from the female combines with ${{\text{I}}^{\text{B}}}$ from the male to form AB blood type having genotype {{\text{I}}^{\text{A}}}$$$${{\text{I}}^{\text{B}}}. But in the heterozygous condition, either ${{\text{I}}^{\text{A}}}$ or i from the female could combine with either ${{\text{I}}^{\text{B}}}$ or i from the male. Thus, the blood types that could be formed are A (${{\text{I}}^{\text{A}}}$i), B (${{\text{I}}^{\text{B}}}$i), AB ({{\text{I}}^{\text{A}}}$$$${{\text{I}}^{\text{B}}}), or O (ii) as shown in the figure below.

Hence, the correct answer is option (D)

Note: Apart from ABO blood grouping, Rh type of blood group determination is also very important. If the Rh antigen is present, then the individual is called Rh-positive, and if the antigen is absent, the individual is called Rh-negative.