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

Options

(a) Three
(b) One
(c) Four
(d) Two

Correct Answer:

Four

Explanation:

The three calle/es in ABO blood groups in humans can produce six different genotypes and four different phenotypes.

Genotypes        Phenotypes

Iᴬ Iᴬ, Iᴬ i               Blood group A

Iᴮ Iᴮ , Iᴮ i               Blood group B

Iᴬ Iᴮ                        Blood group AB

i i                             Blood group O