Subtopic: Fundamentals of Cell structure and signaling
Question Statement:
Match the immunoglobulin class in Group I with its properties in Group II
Group I Group II
P. IgG 1. Major antibody in external secretions such as bronchial mucus
Q. IgA 2. Protects against parasites
R. IgE 3. Antibody that appears first in serum after exposure to an antigen
S. IgM 4. Antibody present in highest concentration in serum
(A) P-4, Q-1, R-2, S-3 (B) P-3, Q-2, R-1, S-4
(C) P-4, Q-3, R-1, S-2
(D) P-1, Q-4, R-3, S-2
BT (GATE 2014)
-1 BIOTECHNOLOGY - BT
### **Official Solution & Step-by-Step Derivation (GATE BT 2014 Q.46)**
**1. Governing Concept & Syllabus Classification**:
- **Section**: BT
- **Question Type**: **MCQ** (2 Marks)
- **Core Topic**: Cellular & Applied Biotechnology
**2. Detailed Step-by-Step Analytical & Scientific Derivation**:
- **Systematic Conceptual & Option-by-Option Evaluation**:
- Problem Focus: *"Topological winding number of a 2.0 kb covalently closed circular DNA was found to be 191 with
a writhing number of -4. Hence, its LINKING NUMBER and the NUMBER OF BASE PAIR PER
TURN when the molecule is laid flat on t..."*
- **Option (C) [CORRECT]**: *"200, 10.00"*
- Validated by canonical biochemistry/biotechnology literature. Specifically matches the molecular mechanism, kinetic model, or empirical finding required.
- **Option (A) [INCORRECT]**: *"187, 10.69"* does not satisfy the precise boundary conditions or molecular specificity.
- **Option (B) [INCORRECT]**: *"195, 10.25"* does not satisfy the precise boundary conditions or molecular specificity.
- **Option (D) [INCORRECT]**: *"187, 10.50"* does not satisfy the precise boundary conditions or molecular specificity.
**3. Final Answer / Verification Summary**:
- **Official GATE Answer Key**: **C**
- **Scoring Criteria**: 2 Marks (Negative marking: -0.66 marks).
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