Question

The example of ABO blood grouping also provides a good example of multiple alleles. Explain it .

Answer 1

Part 1: Introduction of multiple allelism
When a gene has two or more than two alternative variants ( alleles), it is called a multiple allelic gene. Multiple allelism is observed in a population and not in an individual. An individual is diploid, that means, only two alleles of a gene can be present in an individual.

Part 2: Multiple alleles of ABO blood group
The gene responsible for the ABO blood group system is I. This gene exists in three allelic forms - $I^A$, $I^B$ and i. $I^A$ and $I^B$ are dominant alleles and i is the recessive allele. Since, three alleles for ABO blood group are found in a population, it is an example of multiple allelism.