NEET 2020
- Exam
- NEET
- Year
- 2020
- Subject
- Zoology
- Chapter
- Principles of Inheritance and Variation
NEET 2020 · Zoology · Principles of Inheritance and Variation
Identify the wrong statement with reference to the gene...
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 IA and IB 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 IA and IB are present together, they express same type of sugar.
Step-by-step solution
For the ABO system of blood groups, allele IA 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 IB 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 IA and IB are present in a person, both enzymes thus both antigens A and B are produced. This is because of co-dominance. These antigens determine the type of AB blood group.