Question

: A child of blood group O cannot have parents of blood groups
a) AB and AB/O
b) A and B
c) B and B
d) O and O

Answer 1

The ABO system has four major blood groups –A,B,AB,O. The child can have a blood type different from its parents. The A and B genes are dominant and the O gene is recessive. Example if an O gene is paired with an A gene the blood type will be A.

Complete answer:
The blood group in humans is determined by the ABO blood system devised by karl Landsteiner. The ABO blood type chart can be used to predict the possibility of paternity.
If the mother's blood type is A, and the father's blood type is B, then the,Possible alleles from the mother are ${I^A}$ or ${I^O}$. Possible alleles from father are ${I^B}$ or ${I^O}$ hence blood types are A or O.
If the mother's blood type is B, and the father's blood type is B, then the,Possible alleles from mother are ${I^A}$ and ${I^O}$. Possible alleles from father are ${I^B}$ and ${I^O}$ hence gives blood type A or B or O.
If the mother's blood type is O, and the father's blood type is O, then the,Possible alleles from the mother are ${I^O}$. Possible alleles from father are ${I^O}$ hence blood type is O.
If the mother's blood type is AB, and the father's blood type is AB, then the possible alleles from mother are ${I^A}$ or ${I^B}$. Possible alleles from father are ${I^A}$ or ${I^B}$ hence blood types are A or B or AB.
If the mother's blood type is AB, and the father's blood type is O, then each biological parent donates one of their two ABO alleles to their child. A mother who is blood type AB could pass either an A or a B to the child. A father who is blood type O can only pass O.

So, the correct answer is option A.

Note: A baby’s probable blood group is mainly determined by the mother and the father's genes. Knowing the exact blood group of the unborn baby is not possible. Your blood type is based on the presence or absence of the A and B antigens on red blood cells.