The Question is from neet-botany respiration-in-plants aerobic-respiration, and it was created by the author Mr. NARESH KUMAR K

Question

In the context of aerobic respiration, uncoupling agents like 2,4-dinitrophenol (DNP) disrupt ATP synthesis by:

Mr. NARESH KUMAR K · Accepted Answer

## CORE INFORMATION
✓ **Answer**: B
## CONCEPT FRAMEWORK
 **Primary Concept**: Oxidative Phosphorylation and Chemiosmosis
 **Related Topics**: Electron Transport Chain, ATP Synthase, Mitochondrial Membrane, Uncoupling Agents
 **Prerequisites**: Understanding of the process of aerobic respiration, particularly the role of the proton gradient in ATP synthesis.
## SOLUTION PATHWAY
**Given Information**:
  Uncoupling agent: 2,4-dinitrophenol (DNP)
  Process: Aerobic respiration
  Effect: Disruption of ATP synthesis
**Method & Steps**:
 1. Understanding the mechanism of ATP synthesis in oxidative phosphorylation.
  Reasoning: ATP synthesis in mitochondria relies on the chemiosmotic theory.  Electrons are passed down the electron transport chain (ETC), pumping protons ($H^+$) from the mitochondrial matrix to the intermembrane space, creating a proton gradient.
  Formula/Rule:  The proton motive force (PMF), driven by this gradient, provides the energy for ATP synthase to synthesize ATP from ADP and inorganic phosphate ($P_i$).
 2. Analyzing the effect of uncoupling agents.
  Working: Uncoupling agents like DNP disrupt the proton gradient by carrying protons across the inner mitochondrial membrane, bypassing ATP synthase.  This dissipates the proton motive force, reducing ATP production without affecting the electron transport chain itself.
  Key Point: The energy from the electron transport chain is released as heat instead of being used for ATP synthesis.
 3. Evaluating the options.
  Result: Option B correctly describes the mechanism of DNP. It dissipates the proton gradient, preventing the efficient use of the proton motive force for ATP synthesis.
  Verification: The other options are incorrect because DNP does not directly inhibit the electron transport chain, block NADH binding, or directly inhibit ATP synthase. It acts by uncoupling the proton gradient from ATP synthesis.
 ## OPTION ANALYSIS
A :x: Inhibiting the electron transport chain is incorrect. DNP does not directly impede the electron transport chain; it affects the subsequent utilization of the generated proton gradient.
B ✓: Dissipating the proton gradient across the inner mitochondrial membrane is correct. This is the primary mechanism of action for DNP and other uncoupling agents.
C :x: Blocking the binding of NADH to Complex I is incorrect. DNP does not interfere with the binding of NADH to Complex I.
D :x: Inhibiting the activity of ATP synthase directly is incorrect. DNP does not directly inhibit ATP synthase; it prevents it from functioning effectively by dissipating the proton gradient that drives it.
 ## LEARNING AIDS
 **Common Mistakes**:
  1.Confusing uncoupling agents with ETC inhibitors:  Uncoupling agents don't block electron flow; they short-circuit the proton gradient.
  2.Thinking DNP directly inhibits ATP synthase: DNP indirectly affects ATP synthase by reducing the proton gradient.
 **Quick Tips**:
  1.Remember that uncoupling agents dissipate the proton gradient, leading to heat generation instead of ATP production.
  2.Visualize the inner mitochondrial membrane and the proton gradient to understand how DNP works.

Mr. NARESH KUMAR K · Answer

Inhibiting the electron transport chain

Mr. NARESH KUMAR K · Answer

The correct Option is "Dissipating the proton gradient across the inner mitochondrial membrane"

Mr. NARESH KUMAR K · Answer

Blocking the binding of NADH to Complex I

Mr. NARESH KUMAR K · Answer

Inhibiting the activity of ATP synthase directly

NEET Botany Respiration in Plants Aerobic Respiration MCQs

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