NEET2020ZoologyPrinciples of Inheritance and VariationActual
Identify the wrong statement with reference to the gene ‘I’ that controls ABO blood groups.
Options
- AA person will have only two of the three alleles.
- BWhen I A and I B are present together, they express same type of sugar.
- CAllele ‘i’ does not produce any sugar
- DThe gene (I) has three alleles.
Correct answer
B. When I A and I B are present together, they express same type of sugar.
Step-by-step solution
For the ABO system of blood groups, allele I A produces N acetylgalactosamyl transferase enzyme which recognizes H antigen present in RBC membrane and adds N-acetylgalactosamine to sugar part of H antigen to form A antigen. The allele I B produces galactosyl transferase enzyme which adds galactose o the sugar part of H antigen to form B antigen. Allele 'i' does not produce any sugar or antigen. When both I A and I B are present in a person, both enzymes thus both antigens A and B are produced. This is becau