Question

A female with blood type O is the mother of a child with blood type A and dies in a tragic accident. Four individuals claim the paternity of the child. Male A is blood type A, male B is blood type B, Male C is blood type 0 and Male D is type AB. Based on the blood test only, which individual(s) COULD be the father of the child? Mark all that apply Select one or more: a. None of the males can be the father b. Male B c. Male C d. Male A e. Male D

Answer 1

Answer- d. Male A &  e. Male D

For the blood group of offspring , gene of mother and father both cotribute. Blood group is controlled by single gene having three allelic forms i, I^A , I^B. For blood group A , antigen A is present on RBCs. For Blood group B, anigen B is present on RBCs. For AB blood group, both A and B antigen are present on RBCs while for O blood group, antigen is absents on RBCs.

As blood group of mother is O ,Genotype of Mother is i i

The blood group of child is A , his genotype is either i I^A or I^A I^A But as maternal gene is i genotype of child is i I^A.

The I^A gene is paternal means came from father . Father with blood group A ( i I^A or  I^A I^A ) or AB ( I^AI^B) can contribute I^A gene to child.

As father with blood group B and O do not have I^A gene they are not responsible for A type of blood group.