Question

Evolution of different blood groups occurred due to

• A. Genetic variation
• B. Genetic drift
• C. Both A and B
• D. All of the above

Answer 1

The correct option is A Genetic variation

On the basis of antigens located on the surface of RBCs, several blood groups have been defined. Each blood group is determined by a set of different genes. The two medically important blood groups are ABO and Rh systems.

ABO Blood Groups:

A set of three multiple alleles on the chromosome 9 is responsible for the four blood types i.e., A, B, AB and O groups. The genes controlling the blood types have been designated as I ( standing for isohaemogglutinin )

Rh Blood Groups:

The Rh factor is found only in humans and rhesus monkey. The Rh blood group is determined by at least three genes ( C, D and E ) located on the chromosome 1 each with two alleles ( C,c ; D,d; E,e ) making a large number of genotypic combinations possible.

Individuals having Rh factor are called Rh positive and those lacking Rh factor are called Rh negative.

Hence, different blood groups are determined according to the genes controlling them so they show variation at the genetic level.

So, the correct answer is A.