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Question #46731
The Question
Tetrodotoxin (TTX) is a potent neurotoxin that specifically blocks voltage-gated Na+ channels on the axolemma. If an afferent neuron in a reflex arc is exposed to TTX, all of the following physiological consequences will occur, EXCEPT:
Options
- A.
The depolarization phase of the action potential is aborted due to the inability of Na+ to passively diffuse into the axoplasm.
- B.
Voltage-gated Ca2+ channels at the synaptic knob fail to open, preventing the exocytosis of neurotransmitters.
- C.
The resting membrane potential collapses towards zero because the Na+/K+ ATPase pump is secondarily inhibited.
- D.
The polysynaptic contralateral pathways required for complex motor coordination fail to receive excitatory signals.
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
Action Potential Threshold Logic|Ipsilateral vs Contralateral Signaling
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Distinguishing between the proteins responsible for maintaining the resting membrane potential (Na+/K+ pump, leak channels) versus those responsible for generating the action potential (voltage-gated channels).
The common misconception is that blocking action potentials or using a neurotoxin leads to a total collapse of all membrane transport, including the ATP-dependent Na+/K+ pump.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Cell – The Unit of Life - Class 11 |
| Concept | Active vs Passive Gradient Logic |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |