P, Q, R and S are four types of dangerous microbes recently found in a human habitat. The area of
each circle with its diameter printed in brackets represents the growth of a single microbe surviving
human immunity system within 24 hours of entering the body. The danger to human beings varies
proportionately with the toxicity, potency and growth attributed to a microbe shown in the figure
below:
1000
P (50 mm)
800
600
Toxicity
400
@ (40 mm)
R (30 mm)
S (20 mm)
200
half of the body mass in kilograms)
(milligrams of microbe required to destroy
Options:
(A) P
(B) Q
(C) R
(D) S
Official Answer Key:
D
Step-by-Step Solution & Explanation
### **Official Solution & Step-by-Step Derivation (GATE BT 2011 Q.65)**
**1. Governing Concept & Syllabus Classification**:
- **Section**: General Aptitude
- **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: *"P, Q, R and S are four types of dangerous microbes recently found in a human habitat. The area of
each circle with its diameter printed in brackets represents the growth of a single microbe surviving
human immunity syste..."*
- **Option (D) [CORRECT]**: *"S
END OF THE QUESTION PAPER
13/16"*
- Validated by canonical biochemistry/biotechnology literature. Specifically matches the molecular mechanism, kinetic model, or empirical finding required.
- **Option (A) [INCORRECT]**: *"P"* does not satisfy the precise boundary conditions or molecular specificity.
- **Option (B) [INCORRECT]**: *"Q"* does not satisfy the precise boundary conditions or molecular specificity.
- **Option (C) [INCORRECT]**: *"R"* 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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