Question

If the blood group of father is 'A' and that of mother is 'B' , the blood group of child could be
A. A or B or AB
B. AB only
C. A or B or AB or O
D. A or B only

Answer 1

Blood groups can be known theoretically by the ABO blood group system. This was first discovered by Karl Landsteiner. There are four blood groups namely A, B, AB and O which have their respective antigens. The blood group can be known by the genes which we inherit from our parents. These blood types are also present in other primates such as monkeys and apes

Complete answer:
Let us see how the antigens are present in different blood groups. In blood group A, the antigen A is present on the red blood cells and anti- B antibodies are present in the serum. In blood group B, the antigen B is present on the RBC and anti-B antibodies are seen in the serum. In AB blood group, both A and B antigens are present on the cells and no antibodies are seen in the serum whereas in O blood group, no antigens are present and both anti- A and anti-B antibodies can be seen in the plasma. Here, the blood group of father is A which who can have two possible genotypes namely ${i^A}{i^A}$ and ${i^O}{i^A}$ whereas the blood group of mother is B who can have ${i^B}{i^B}$ and${i^B}{i^O}$. Thus there are three genes involved; it can together make six genotypes which are ${i^A}{i^A},\;{i^B}{i^B},\;{i^A}{i^B},\;{i^O}{i^O},\;{i^A}{i^O},\;{i^B}{i^O}$. These genotypes ${i^A}{i^A},{i^A}{i^O}$ represent A blood group and the genotypes ${i^B}{i^B},{i^B}{i^O}$ represent blood group B, the genotypes${i^A}{i^B}$ represent AB blood group and the genotype ${i^O}{i^O}$ represent O blood group. So, the parents with above mentioned blood groups can possibly give birth to the child having these genotypes.

Hence the correct option is C

Note:
There is Rh factor which is called as Rhesus factor which is a protein present externally to RBC.
Based on this protein, a person’s blood group can be positive or negative. If this protein is present, then the person is said to be positive, if the protein is absent then the person is negative.