Before You Begin
Question #47437
The Question
Neuromodulators can alter the excitability of a neuron, making it more responsive to temporal summation. If a neuromodulator binds to a G-protein coupled receptor (GPCR) and activates the Phospholipase C pathway, it 'primes' the neuron to fire an action potential at a lower stimulus frequency. All of the following statements correctly describe this physiological cascade EXCEPT:
Options
- A.
The neuromodulator-receptor complex directly opens ligand-gated Na+ channels, causing an immediate Excitatory Postsynaptic Potential (EPSP).
- B.
The activated G-protein stimulates Phospholipase C, which cleaves membrane phospholipids to generate IP3 and DAG.
- C.
Elevated intracellular Ca2+ (released via IP3) and DAG activate protein kinases that phosphorylate specific ion channels.
- D.
The secondary messenger cascade shifts the resting membrane potential closer to the threshold, reducing the need for extensive temporal summation.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Comparative_Analysis
Sharpen your ability to evaluate multiple scenarios and distinguish between competing potential answers.
Concepts Behind This Question
IP3|cAMP|Calcium Signaling
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students frequently confuse the rapid, direct action of classical neurotransmitters (which bind to ionotropic receptors to directly open ion channels) with the slower, indirect action of neuromodulators (which use GPCRs and secondary messengers to alter the baseline excitability or threshold of the neuron).
The trap relies on the word 'directly'.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Neural Control and Coordination - Class 11 |
| Concept | Summation Kinetics |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |