Three distinct antigens X, Y and Z were used to raise antibodies. Antigen Z was injected in a
njection of antigen X was administered on day 70. The antibody titers were monitored in the serut
nouse on day zero followed by the administration of antigens X and Y on day 28. A secon
every day and the results are shown below:
0 14 28
42
56
70
84
98
Which one of the following statements regarding the antibody titers in the serum is INCORRECT?
Options:
(A) Z-specific IgG will be high on day 14
(B) X-specific antibody titer will be high on day 84
(C) X-specific IgG will be high on day 42
(D) Y-specific IgG will be high on day 84
Official Answer Key:
D
Step-by-Step Solution & Explanation
### **Official Solution & Step-by-Step Derivation (GATE BT 2015 Q.59)**
**1. Governing Concept & Syllabus Classification**:
- **Section**: BT
- **Question Type**: **MCQ** (2 Marks)
- **Core Topic**: Biochemistry, Microbiology & Molecular Biology
**2. Detailed Step-by-Step Analytical & Scientific Derivation**:
- **Systematic Conceptual & Option-by-Option Evaluation**:
- Problem Focus: *"Three distinct antigens X, Y and Z were used to raise antibodies. Antigen Z was injected in a
njection of antigen X was administered on day 70. The antibody titers were monitored in the serut
nouse on day zero followed b..."*
- **Option (D) [CORRECT]**: *"Y-specific IgG will be high on day 84
Options :
1.
2
B
--- PAGE 19 ---
3. *
C
4. 0 D"*
- Validated by canonical biochemistry/biotechnology literature. Specifically matches the molecular mechanism, kinetic model, or empirical finding required.
- **Option (A) [INCORRECT]**: *"Z-specific IgG will be high on day 14"* does not satisfy the precise boundary conditions or molecular specificity.
- **Option (B) [INCORRECT]**: *"X-specific antibody titer will be high on day 84"* does not satisfy the precise boundary conditions or molecular specificity.
- **Option (C) [INCORRECT]**: *"X-specific IgG will be high on day 42"* does not satisfy the precise boundary conditions or molecular specificity.
**3. Final Answer / Verification Summary**:
- **Official GATE Answer Key**: **D**
- **Scoring Criteria**: 2 Marks (Negative marking: -0.66 marks).
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