Question

What is the number of alleles for blood group in an individual __________.

• A. 1
• B. 2
• C. 3
• D. 4

Answer 1

The correct option is B 2

ABO blood group in human beings is first discovered by Landsteiner. The fourth blood group, AB was discovered by de Castello and Steni. Bernstein showed that these groups are controlled by three alleles – I^A,I^B and I^O/i. These alleles are autosomal and follow the Mendelian pattern of Inheritance. Alleles I^A, I^B produce a slightly different from of sugar while I^O does not produce any sugar. Because humans are diploid organisms, each person possess any two of the three ‘I’ gene alleles. I^A and I^B are completely dominant over I^O, but when I^A and I^B are present together, they both express their own types of sugar, thus, behaving as codominant alleles.

So, correct answer is option B, ‘2’.