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Question #45911
The Question
A researcher introduces a chemical agent, 2,4-Dinitrophenol (DNP), into a suspension of actively respiring mitochondria. DNP acts as a protonophore, making the inner mitochondrial membrane freely permeable to protons. Which of the following physiological consequences will be observed immediately following the addition of this agent?
Options
- A.
The electron transport chain will halt due to the loss of the electrochemical gradient, stopping the reduction of oxygen at Complex IV.
- B.
The rate of oxygen consumption will increase, accompanied by a rapid decline in the cellular ATP/ADP ratio and increased heat dissipation.
- C.
The F0-F1 ATP synthase will increase its catalytic rate to compensate for the proton leak, maintaining the cellular energy charge.
- D.
The accumulation of reduced coenzymes (NADH and FADH2) will allosterically inhibit the Citric Acid Cycle, leading to hypometabolism.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Regulatory_Failure
Understand how NOT, EXCEPT, and logical constraints are used to manipulate exam results.
Concepts Behind This Question
Inner_Mitochondrial_Membrane|Proton_Gradient|ATP_Synthase
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often confuse 'inhibition of the ETC' (like Cyanide) with 'uncoupling of oxidative phosphorylation' (like DNP).
The common misconception is assuming that if ATP synthesis stops, oxygen consumption must also stop.
The critical NCERT-plus insight is understanding 'respiratory control'—destroying the proton gradient uncouples the two processes, allowing the ETC to run unchecked (increasing O2 consumption) while ATP synthesis fails.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Respiration in Plants - Class 11 |
| Concept | Chemiosmotic ATP Yield |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |