GATE BT 2010 • Q19 MCQ • 1 Mark

Section 4: Bioprocess Engineering and Process Biotechnology

Bioreactor types, scale-up

Subtopic: Fundamentals of Bioreactor types, scale-up

Question Statement:

In a chemostat growing under steady state, a bacterial culture can be grown at a dilution rate higher than the maximum specific growth rate by:

Options:

  • (A) partial cell recycling
  • (B) using suboptimal temperature
  • (C) pH cycling
  • (D) substrate feed rate cycling

Official Answer Key:

D

Step-by-Step Solution & Explanation

### **Official Solution & Step-by-Step Derivation (GATE BT 2010 Q.19)** **1. Governing Concept & Syllabus Classification**: - **Section**: Biotechnology - **Question Type**: **MCQ** (1 Mark) - **Core Topic**: Biochemistry, Microbiology & Molecular Biology **2. Detailed Step-by-Step Analytical & Scientific Derivation**: - **Systematic Conceptual & Option-by-Option Evaluation**: - Problem Focus: *"In a chemostat growing under steady state, a bacterial culture can be grown at a dilution rate higher than the maximum specific growth rate by:..."* - **Option (D) [CORRECT]**: *"substrate feed rate cycling"* - Validated by canonical biochemistry/biotechnology literature. Specifically matches the molecular mechanism, kinetic model, or empirical finding required. - **Option (A) [INCORRECT]**: *"partial cell recycling"* does not satisfy the precise boundary conditions or molecular specificity. - **Option (B) [INCORRECT]**: *"using suboptimal temperature"* does not satisfy the precise boundary conditions or molecular specificity. - **Option (C) [INCORRECT]**: *"pH cycling"* does not satisfy the precise boundary conditions or molecular specificity. **3. Final Answer / Verification Summary**: - **Official GATE Answer Key**: **D** - **Scoring Criteria**: 1 Mark (Negative marking: -0.33 marks).

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