The Question is from neet-zoology , and it was created by the author K SUNKANNA

Question

Which statement regarding the 'I' gene controlling ABO blood groups is INCORRECT?

K SUNKANNA · Accepted Answer

## CORE INFORMATION
✓ **Answer**: [Option Letter B]
## CONCEPT FRAMEWORK
	**Primary Concept**: Genetics of ABO blood groups
	**Related Topics**: Alleles, Antigen expression
	**Prerequisites**: Basic understanding of genetic inheritance
## SOLUTION PATHWAY
**Given Information**:
		- The ABO blood group system is determined by the presence of antigens on the surface of red blood cells.
		- The 'I' gene has three alleles: $I^A$, $I^B$, and $i$.
**Method & Steps**:
	1.	Identify the function of each allele.
		Reasoning: Each allele produces specific sugars that make up the blood group antigens.
		Formula/Rule: $I^A$ produces N-acetylgalactosamine, $I^B$ produces galactose, and $i$ produces no sugars.
	2.	Analyze the given options based on the function of the alleles.
		Working: Assess which options accurately describe the behavior of the alleles.
		Key Point: $I^A$ and $I^B$ can coexist, leading to the expression of both A and B antigens, while 'i' does not contribute any sugar.
	3.	Identify the incorrect statement.
		Result: The statement that says when $I^A$ and $I^B$ are present together they express the same type of sugar is incorrect because they produce different sugars.
		Verification: Option B contradicts the known functions of the alleles.
## OPTION ANALYSIS
[A] ✓: The statement is true; both $I^A$ and $I^B$ express A and B antigens respectively.
[B] :x: This is the incorrect option; $I^A$ and $I^B$ produce different sugars (N-acetylgalactosamine and galactose).
[C] :x: This is true; allele 'i' produces no sugar.
[D] :x: This is true; the gene 'I' has three alleles: $I^A$, $I^B$, and $i$.
## LEARNING AIDS
	**Common Mistakes**:
		1. Confusing the functions of the alleles: Be sure to memorize the specific sugars produced by each allele.
		2. Misinterpreting co-dominance: Remember that both $I^A$ and $I^B$ can be expressed simultaneously, leading to the AB phenotype.
	**Quick Tips**:
		1. Use a Punnett square to visualize the inheritance of ABO blood types.
		2. Remember that the presence of 'i' results in O blood type, while the presence of $I^A$ or $I^B$ leads to A or B blood types respectively.

K SUNKANNA · Answer

When I^A and I^B are present together they express both A and B antigens

K SUNKANNA · Answer

The correct Option is "When I^A and I^B are present together they express same type of sugar"

K SUNKANNA · Answer

Allele 'i' does not produce any sugar

K SUNKANNA · Answer

The gene 'I' has three alleles

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