Question

Choose the correct option.

ABO blood groups in humans are controlled by the gene L. It has three alleles– I^A, I^B and i. Since there are three different alleles, six different genotypes are possible. How many phenotypes can occur?

• A. One
• B. Two
• C. Three
• D. Four

Answer 1

The correct option is D

Four

The correct option is D.

The explanation for the correct option:

1. The blood grouping system in human beings is based on the presence of multiple alleles, which are inherited in a codominant autosomal fashion.
2. The three alleles involved are I^A, I^B, and i. I^A and I^B alleles are dominant compared to the i allele.
3. The type of antigen produced by each allele and the genotype are given in the table below-

Genotype	Antigen	Phenotype
IAIA, IAi	A	A
IBIB, IBi	B	B
IA IB	A, B	AB
ii	O	O

Final answer

The actual number of phenotypes seen during the ABO blood grouping system is four- A, B, AB, and O.