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Question #47430
The Question
A farm worker exposed to a high dose of an organophosphate pesticide presents with severe muscle fasciculations followed by paralysis. Organophosphates are known to inhibit the enzyme acetylcholinesterase (AChE) at the neuromuscular junction. Which of the following best describes the immediate physiological consequence at the postsynaptic membrane?
Options
- A.
Persistent opening of ligand-gated Na+ channels leading to continuous depolarization and subsequent receptor desensitization.
- B.
Blockade of voltage-gated Ca2+ channels at the presynaptic terminal, preventing the exocytosis of acetylcholine.
- C.
Rapid repolarization of the sarcolemma due to the continuous efflux of K+ ions, causing immediate flaccid paralysis.
- D.
Competitive antagonism at the postsynaptic receptors, preventing acetylcholine from generating an end-plate potential.
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
Acetylcholine|Acetylcholinesterase|Synaptic_Cleft
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often assume paralysis only occurs when a neural signal is blocked (e.g., receptor antagonism by Curare).
The trap here is failing to recognize 'depolarizing blockade'—where the inability to clear the neurotransmitter prevents the membrane from repolarizing, leading to continuous stimulation followed by synaptic fatigue and paralysis.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Neural Control and Coordination - Class 11 |
| Concept | Synaptic Vesicle Exocytosis Trigger |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |