Idiotypic determinants of an antibody are associated with the
(A) constant region of the heavy chains (B) constant region of the light chains
(C) variable region (D) constant regions of light and heavy chains
Options:
(A) constant region of the heavy chains
(B) constant region of the light chains
(C) variable region
(D) constant regions of light and heavy chains
Official Answer Key:
C
Step-by-Step Solution & Explanation
### **Official Solution & Step-by-Step Derivation (GATE BT 2012 Q.3)**
**1. Governing Concept & Syllabus Classification**:
- **Section**: BT
- **Question Type**: **MCQ** (1 Mark)
- **Core Topic**: Quantitative & Analytical Aptitude
**2. Detailed Step-by-Step Analytical & Scientific Derivation**:
- **Systematic Conceptual & Option-by-Option Evaluation**:
- Problem Focus: *"Idiotypic determinants of an antibody are associated with the..."*
- **Option (C) [CORRECT]**: *"variable region"*
- Validated by canonical biochemistry/biotechnology literature. Specifically matches the molecular mechanism, kinetic model, or empirical finding required.
- **Option (A) [INCORRECT]**: *"constant region of the heavy chains"* does not satisfy the precise boundary conditions or molecular specificity.
- **Option (B) [INCORRECT]**: *"constant region of the light chains"* does not satisfy the precise boundary conditions or molecular specificity.
- **Option (D) [INCORRECT]**: *"constant regions of light and heavy chains"* does not satisfy the precise boundary conditions or molecular specificity.
**3. Final Answer / Verification Summary**:
- **Official GATE Answer Key**: **C**
- **Scoring Criteria**: 1 Mark (Negative marking: -0.33 marks).
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