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Question #47434
The Question
A mammalian herbivore grazes exclusively on plants grown in soil with severe potassium deficiency, eventually developing systemic hypokalemia. Based on the principles of neural electrophysiology, which of the following best describes the primary impact of this condition on the organism's neuronal action potentials?
Options
- A.
The resting membrane potential becomes more negative due to a steeper K+ efflux gradient, increasing the stimulus required to reach the threshold and slowing the neuronal firing rate.
- B.
The repolarization phase is accelerated because of a reduced extracellular K+ concentration, which shortens the synaptic delay and increases the neuronal firing rate.
- C.
The Na+/K+ ATPase pump reverses its stoichiometry to compensate for the deficiency, leading to a permanent state of axonal depolarization.
- D.
Voltage-gated Ca2+ channels at the synaptic knob fail to open, directly preventing neurotransmitter release without altering the axonal resting membrane 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
Synaptic Delay Determinant|Nutrient Immobility|Sodium-Potassium Pump
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students frequently confuse the effects of hypokalemia with hypocalcemia.
A common misconception is that low extracellular K+ would reduce K+ efflux.
However, according to the Nernst equation, lowering extracellular K+ actually steepens the outward concentration gradient, causing hyperpolarization.
This makes the threshold harder to reach, contrasting with hypocalcemia which lowers the threshold and causes tetany.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Neural Control and Coordination - Class 11 |
| Concept | Synaptic Delay Determinant |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |