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

Hint: 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.