Neuronal signaling MCQs With Answer

Neuronal signaling MCQs With Answer

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Neuronal signaling MCQs With Answer is designed for M.Pharm students aiming to deepen their understanding of neuronal communication at molecular, cellular and pharmacological levels. This quiz compilation covers core concepts such as ion channel function, synaptic vesicle cycling, receptor types and signaling cascades, synaptic plasticity mechanisms (LTP/LTD), neurotransmitter metabolism and transport, and modern experimental tools used in neuropharmacology. Each question emphasizes mechanistic details and translational relevance to drug targeting and toxicology. Use these MCQs to test critical thinking, prepare for exams and identify areas needing review; answers are provided immediately after each question to support active learning and rapid self-assessment.

Q1. Which ion flux through voltage-gated channels is primarily responsible for the rapid depolarization phase of a neuronal action potential?

  • Sodium influx through voltage-gated Na+ channels
  • Potassium efflux through voltage-gated K+ channels
  • Calcium influx through voltage-gated Ca2+ channels
  • Chloride influx through GABA-gated channels

Correct Answer: Sodium influx through voltage-gated Na+ channels

Q2. The resting membrane potential of a typical neuron is most closely determined by which of the following?

  • The equilibrium potential for potassium and high resting K+ permeability
  • The equilibrium potential for sodium and high resting Na+ permeability
  • Uniform permeability to Na+, K+ and Cl-
  • Continuous calcium influx through ligand-gated channels

Correct Answer: The equilibrium potential for potassium and high resting K+ permeability

Q3. Which marine-derived toxin is classically known for binding the outer pore of voltage-gated sodium channels and blocking action potential initiation?

  • Tetrodotoxin (TTX)
  • Batrachotoxin
  • Tetraethylammonium
  • Conotoxin

Correct Answer: Tetrodotoxin (TTX)

Q4. Which protein functions as the principal calcium sensor that triggers fast, synchronous synaptic vesicle exocytosis?

  • Synaptotagmin
  • Synaptobrevin (VAMP)
  • SNAP-25
  • Syntaxin

Correct Answer: Synaptotagmin

Q5. Botulinum neurotoxins inhibit neurotransmitter release primarily by cleaving which presynaptic SNARE protein (noting serotype A specificity)?

  • SNAP-25
  • Synaptobrevin (VAMP)
  • Syntaxin
  • Synaptotagmin

Correct Answer: SNAP-25

Q6. Induction of classical hippocampal long-term potentiation (LTP) at Schaffer collateral–CA1 synapses critically requires activation of which receptor type?

  • NMDA-type glutamate receptors
  • AMPA-type glutamate receptors
  • GABA-A receptors
  • Metabotropic glutamate receptor 1 (mGluR1)

Correct Answer: NMDA-type glutamate receptors

Q7. What unique property of NMDA receptors makes them coincidence detectors crucial for synaptic plasticity?

  • Voltage-dependent Mg2+ block relieved by postsynaptic depolarization
  • Permeability exclusively to chloride ions
  • Activation by glutamate alone without co-agonist requirement
  • Direct coupling to heterotrimeric G-proteins

Correct Answer: Voltage-dependent Mg2+ block relieved by postsynaptic depolarization

Q8. Which intracellular second messenger directly binds and activates protein kinase A (PKA)?

  • Cyclic AMP (cAMP)
  • Cyclic GMP (cGMP)
  • Inositol 1,4,5-trisphosphate (IP3)
  • Diacylglycerol (DAG)

Correct Answer: Cyclic AMP (cAMP)

Q9. Which enzyme family terminates cAMP signaling by converting cAMP to AMP?

  • Phosphodiesterases
  • Adenylyl cyclases
  • Protein kinases (PKA)
  • Phospholipases

Correct Answer: Phosphodiesterases

Q10. When calculating the equilibrium potential for a single ion species across a membrane, which equation is most appropriate?

  • The Nernst equation
  • The Goldman–Hodgkin–Katz voltage equation
  • The Michaelis–Menten equation
  • The Henderson–Hasselbalch equation

Correct Answer: The Nernst equation

Q11. Which process describes rapid termination of synaptic signaling by transporter-mediated clearance of neurotransmitter back into presynaptic terminals or glia?

  • Reuptake by specific plasma membrane transporters
  • Diffusion away from the synaptic cleft
  • Proteolytic cleavage within the cleft
  • Endocytosis of postsynaptic receptors

Correct Answer: Reuptake by specific plasma membrane transporters

Q12. The voltage-clamp experimental technique is used primarily to measure which of the following?

  • Membrane ionic currents while holding membrane potential constant
  • Changes in membrane potential while allowing currents to vary freely
  • Intracellular calcium concentrations in response to stimulation
  • Synaptic vesicle fusion kinetics using fluorescence

Correct Answer: Membrane ionic currents while holding membrane potential constant

Q13. Fast anterograde axonal transport of synaptic vesicle precursors along microtubules is driven mainly by which motor protein?

  • Kinesin
  • Dynein
  • Myosin V
  • Dynamin

Correct Answer: Kinesin

Q14. Which receptor family mediates the fastest synaptic transmission by forming ion-permeable pores that open upon ligand binding?

  • Ionotropic receptors
  • Metabotropic G-protein-coupled receptors
  • Receptor tyrosine kinases
  • Nuclear hormone receptors

Correct Answer: Ionotropic receptors

Q15. PSD-95, a major postsynaptic scaffold protein, primarily functions to do which of the following at excitatory synapses?

  • Cluster and stabilize glutamate receptors and signaling complexes
  • Mediate vesicle docking at the presynaptic active zone
  • Act as a serine/threonine kinase to phosphorylate AMPA receptors
  • Degrade excess neurotransmitter in the synaptic cleft

Correct Answer: Cluster and stabilize glutamate receptors and signaling complexes

Q16. During sustained high-frequency stimulation, a rapid decline in synaptic strength occurring over seconds to minutes is most commonly attributed to which presynaptic mechanism?

  • Depletion of readily releasable synaptic vesicle pool
  • Immediate postsynaptic receptor internalization
  • Upregulation of neurotransmitter synthesis
  • Enhanced calcium buffering that increases release probability

Correct Answer: Depletion of readily releasable synaptic vesicle pool

Q17. Which enzyme localized to the mitochondrial outer membrane in presynaptic terminals oxidatively deaminates monoamine neurotransmitters such as dopamine and serotonin?

  • Monoamine oxidase (MAO)
  • Catechol-O-methyltransferase (COMT)
  • Acetylcholinesterase (AChE)
  • Tyrosine hydroxylase

Correct Answer: Monoamine oxidase (MAO)

Q18. Fast inhibitory postsynaptic currents mediated by GABA-A receptors are primarily carried by flux of which ion?

  • Chloride (Cl-)
  • Potassium (K+)
  • Sodium (Na+)
  • Calcium (Ca2+)

Correct Answer: Chloride (Cl-)

Q19. Phosphorylation of G protein–coupled receptors (GPCRs) by GRKs typically results in which downstream event affecting receptor signaling?

  • Recruitment of arrestin leading to desensitization and internalization
  • Increased G-protein coupling and amplified signaling
  • Immediate receptor-mediated ion channel opening
  • Conversion of the receptor into a tyrosine kinase

Correct Answer: Recruitment of arrestin leading to desensitization and internalization

Q20. In optogenetics, which light-activated microbial protein is commonly used as a cation channel to depolarize and drive action potentials in neurons?

  • Channelrhodopsin-2 (ChR2)
  • Halorhodopsin (NpHR)
  • Archaerhodopsin (Arch)
  • Rhodopsin kinase

Correct Answer: Channelrhodopsin-2 (ChR2)

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