GATE BT 2012 • Q48 MCQ • 2 Marks

Section 2: General Biotechnology

Bioenergetics and Metabolism

Subtopic: Thermodynamics & ATP Bioenergetics

Question Statement:

The free energy change for the transport of three Na+ out of the cell is (A) +1.5 kJ/mol (B) +17.4 kJ/mol (C) +18.9 kJ/mol (D) +36.3 kJ/mol

Options:

  • (A) +1.5 kJ/mol
  • (B) +17.4 kJ/mol
  • (C) +18.9 kJ/mol
  • (D) +36.3 kJ/mol

Official Answer Key:

D

Step-by-Step Solution & Explanation

### **Official Solution & Step-by-Step Derivation (GATE BT 2012 Q.48)** **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: *"The free energy change for the transport of three Na+ out of the cell is..."* - **Option (D) [CORRECT]**: *"+36.3 kJ/mol"* - Validated by canonical biochemistry/biotechnology literature. Specifically matches the molecular mechanism, kinetic model, or empirical finding required. - **Option (A) [INCORRECT]**: *"+1.5 kJ/mol"* does not satisfy the precise boundary conditions or molecular specificity. - **Option (B) [INCORRECT]**: *"+17.4 kJ/mol"* does not satisfy the precise boundary conditions or molecular specificity. - **Option (C) [INCORRECT]**: *"+18.9 kJ/mol"* 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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