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Question #45913
The Question
Cyanide acts as a potent metabolic poison by irreversibly binding to the ferric ion (Fe3+) of cytochrome a3 in Complex IV of the mitochondrial electron transport chain. If a respiring plant cell is exposed to cyanide, which of the following represents an INCORRECT physiological consequence?
Options
- A.
The terminal reduction of molecular oxygen to metabolic water is completely blocked.
- B.
The proton gradient across the inner mitochondrial membrane is maintained by the continued operation of Complexes I and III.
- C.
Mobile electron carriers such as Ubiquinone and Cytochrome c rapidly accumulate in their reduced states.
- D.
Oxidative phosphorylation ceases entirely despite the presence of adequate intracellular molecular oxygen.
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
Cytochrome_c_Oxidase|Cytochrome_a3|Oxygen
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Understanding the ETC as an obligate, coupled sequential chain rather than a series of independent proton pumps.
Common Misconception: Students often erroneously assume that if Complex IV is blocked, the earlier complexes (I and III) can continue to pump protons as long as NADH/FADH2 is available.
They fail to realize that without the terminal electron acceptor clearing the chain, all carriers become fully reduced, stalling the entire system.
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 |