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Question #47428

Difficulty: 8/10 | 🟢 Free

The Question

Tetrodotoxin (TTX) is a potent neurotoxin that specifically occludes voltage-gated $Na^+$ channels on the axonal membrane. If an isolated mammalian neuron is exposed to TTX and subsequently subjected to a supra-threshold electrical stimulus, all of the following physiological conditions will be observed, EXCEPT:

Options

A.
The resting membrane potential remains polarized due to the unaffected $Na^+$ / $K^+$ ATPase pump.
B.
The rapid influx of $Na^+$ ions responsible for the depolarizing phase is completely halted.
C.
Voltage-gated $K^+$ channels open to initiate repolarization as a compensatory mechanism.
D.
The neuron fails to propagate the action potential, effectively blocking signal transmission.

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

Na+/K+ ATPase|Voltage_Gated_Sodium_Channel|Action_Potential

Why This Question Is Tricky

Common Mistakes

Conceptual Pivot: Students often memorize the sequence of an action potential (Depolarization -> Repolarization) and might assume that if one phase is blocked, the cell will 'compensate' by activating the next phase to restore ionic balance.

This traps students who fail to realize that the opening of voltage-gated $K^+$ channels is strictly contingent upon the prior depolarization event reaching a specific positive voltage threshold.

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