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Question #47671
The Question
An aerobic organism is exposed to a chemical toxin (such as 2,4-Dinitrophenol) that makes the inner mitochondrial membrane freely permeable to protons. Which of the following statements correctly describes the subsequent physiological and ecological consequences?
Options
- A.
Oxygen consumption ceases and the TCA cycle halts due to a lack of oxidized NAD+, leading to a rapid decline in the standing crop.
- B.
Electron transport continues with increased oxygen consumption, the TCA cycle flux accelerates, and the respiratory substrate demand per unit of standing crop biomass increases.
- C.
ATP synthesis increases due to rapid proton diffusion, the TCA cycle stoichiometry is altered to yield more FADH2, and the standing crop remains unaffected.
- D.
Both the electron transport chain and ATP synthase activity halt, leading to a shift towards anaerobic respiration and a decrease in maintenance costs.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Comparative_Analysis
Sharpen your ability to evaluate multiple scenarios and distinguish between competing potential answers.
Concepts Behind This Question
Electron Transport Chain|NADH Dehydrogenase|DNP
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often mistakenly believe that if ATP synthesis stops, the entire ETC and TCA cycle must also stop.
The trap is failing to distinguish between 'coupled' and 'uncoupled' respiration.
In uncoupled respiration, oxidation (ETC) continues and even accelerates because the proton motive force (which normally exerts back-pressure) is dissipated.
This leads to a hyper-metabolic state where the organism rapidly burns through its standing crop biomass without yielding proportional ATP.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Respiration in Plants - Class 11 |
| Concept | TCA Cycle Stoichiometry |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |