Karnatak PGET 2007 Forensic Medicine MCQ Answer 2

The correct Answer is D

Around 1900 it was discovered that there are at least 4 different kinds of human blood. This is based on the fact that on the surface of the red blood cells there may be one or more proteins, called antigens. These antigens are called A and B. Antibodies are produced in the blood plasma against these A and B antigens, and continue to be produced throughout a person’s life.

The antigens determining the four blood groups are the result of the expression of three alleles; O, A and B; the latter two being dominant to O. The genotypes AA and AO, and the genotypes BB and BO cannot be distinguished serologically and are classified as group A and B respectively. Thus only four phenotypes (A, B, AB, and O) can be recognized, although six genotypes occur.

A person’s blood type is inherited from their parents, just like any other genetic trait.

Persons with blood type A have inherited one or two copies of the gene for the A antigen, one from each parent. Persons with blood type B have inherited one or two copies of the gene for the B antigen. Persons with blood type AB have inherited on copy of the A antigen from one parent and one copy of the B antigen gene from the other parent. Persons with blood type O inherited neither A nor B genes from their parents.

Blood typing can be used in legal situations involving identification or disputed paternity. In paternity cases a comparison of the blood types of mother, child, and alleged father may be used to exclude a man as the possible parent of a child. For example, a child with the blood type AB whose mother is type A could not have a father whose blood type is A or O. The father must have blood type B.

An interesting link regarding disputed paternity

Category: Karnataka PGET 2007 MCQs