UTSC NROB61 Neurophysiology: Exam 2 - Questions with
Correct Answers
50 questions
1. Divergence in neural circuits means:
A. Many neurons converge on one neuron
B. Neurons fire in isolation
C. One neuron sends output to many neurons
D. Signals travel backward
Correct Answer: C. One neuron sends output to many neurons
Rationale: Convergence is the opposite.
2. An electrode placed inside a neuron records:
A. Only extracellular field potentials
B. Only light signals
C. Only Ca2+ concentration
D. Intracellular membrane potential
Correct Answer: D. Intracellular membrane potential
Rationale: Sharp or whole-cell electrodes measure Vm.
3. Neurotransmitter release occurs at the:
A. Dendritic spine head
B. Node of Ranvier
C. Presynaptic terminal
D. Nucleus
Correct Answer: C. Presynaptic terminal
Rationale: Vesicles fuse at active zones.
4. A stronger sustained stimulus to a sensory neuron is usually encoded as:
A. A larger action potential amplitude
B. A longer action potential
C. A higher action potential frequency
D. A slower conduction velocity
Correct Answer: C. A higher action potential frequency
Rationale: Action potentials are all-or-none, so intensity is rate-coded.
5. Neher and Sakmann received the Nobel Prize (1991) for:
A. Developing the patch clamp technique
B. Describing LTP
C. Discovering myelin
D. Describing receptive fields
Correct Answer: A. Developing the patch clamp technique
Rationale: Single channel recording.
6. Fast inactivation of voltage-gated Na+ channels is mediated by:
A. The intracellular III-IV linker (hinged lid)
B. The S4 segment alone
C. Extracellular glycosylation
D. The selectivity filter
Correct Answer: A. The intracellular III-IV linker (hinged lid)
Rationale: The IFM motif plugs the pore.
, 7. Perforated-patch recording (with nystatin or amphotericin) is used to:
A. Seal glass to membrane
B. Measure single channels only
C. Record whole-cell currents while preserving intracellular messengers
D. Block all channels
Correct Answer: C. Record whole-cell currents while preserving intracellular messengers
Rationale: Small pores let ions through but not larger molecules.
8. The voltage sensor of voltage-gated channels is the:
A. S4 transmembrane segment
B. P loop
C. S6 segment only
D. N-terminal ball
Correct Answer: A. S4 transmembrane segment
Rationale: Positive charges move with voltage.
9. Which gradient drives K+ out of a resting neuron?
A. The concentration gradient, partly opposed by the electrical gradient
B. Only the electrical gradient
C. ATP hydrolysis
D. Ca2+ binding
Correct Answer: A. The concentration gradient, partly opposed by the electrical gradient
Rationale: Inside negativity opposes K+ efflux.
10. Using GHK with PK:PNa = 1:0.04, Vm will be:
A. Exactly EK
B. Close to ENa
C. 0 mV
D. Slightly less negative than EK
Correct Answer: D. Slightly less negative than EK
Rationale: Small Na+ permeability depolarizes slightly.
11. The pump is called electrogenic because it:
A. Moves net positive charge out, slightly hyperpolarizing the cell
B. Generates action potentials
C. Moves no net charge
D. Depolarizes the cell
Correct Answer: A. Moves net positive charge out, slightly hyperpolarizing the cell
Rationale: Contributes a few millivolts.
12. At the resting potential (-70 mV), the net driving force on Na+ is:
A. Outward
B. Zero
C. Weakly outward
D. Strongly inward
Correct Answer: D. Strongly inward
Rationale: Both gradients push Na+ in.
Correct Answers
50 questions
1. Divergence in neural circuits means:
A. Many neurons converge on one neuron
B. Neurons fire in isolation
C. One neuron sends output to many neurons
D. Signals travel backward
Correct Answer: C. One neuron sends output to many neurons
Rationale: Convergence is the opposite.
2. An electrode placed inside a neuron records:
A. Only extracellular field potentials
B. Only light signals
C. Only Ca2+ concentration
D. Intracellular membrane potential
Correct Answer: D. Intracellular membrane potential
Rationale: Sharp or whole-cell electrodes measure Vm.
3. Neurotransmitter release occurs at the:
A. Dendritic spine head
B. Node of Ranvier
C. Presynaptic terminal
D. Nucleus
Correct Answer: C. Presynaptic terminal
Rationale: Vesicles fuse at active zones.
4. A stronger sustained stimulus to a sensory neuron is usually encoded as:
A. A larger action potential amplitude
B. A longer action potential
C. A higher action potential frequency
D. A slower conduction velocity
Correct Answer: C. A higher action potential frequency
Rationale: Action potentials are all-or-none, so intensity is rate-coded.
5. Neher and Sakmann received the Nobel Prize (1991) for:
A. Developing the patch clamp technique
B. Describing LTP
C. Discovering myelin
D. Describing receptive fields
Correct Answer: A. Developing the patch clamp technique
Rationale: Single channel recording.
6. Fast inactivation of voltage-gated Na+ channels is mediated by:
A. The intracellular III-IV linker (hinged lid)
B. The S4 segment alone
C. Extracellular glycosylation
D. The selectivity filter
Correct Answer: A. The intracellular III-IV linker (hinged lid)
Rationale: The IFM motif plugs the pore.
, 7. Perforated-patch recording (with nystatin or amphotericin) is used to:
A. Seal glass to membrane
B. Measure single channels only
C. Record whole-cell currents while preserving intracellular messengers
D. Block all channels
Correct Answer: C. Record whole-cell currents while preserving intracellular messengers
Rationale: Small pores let ions through but not larger molecules.
8. The voltage sensor of voltage-gated channels is the:
A. S4 transmembrane segment
B. P loop
C. S6 segment only
D. N-terminal ball
Correct Answer: A. S4 transmembrane segment
Rationale: Positive charges move with voltage.
9. Which gradient drives K+ out of a resting neuron?
A. The concentration gradient, partly opposed by the electrical gradient
B. Only the electrical gradient
C. ATP hydrolysis
D. Ca2+ binding
Correct Answer: A. The concentration gradient, partly opposed by the electrical gradient
Rationale: Inside negativity opposes K+ efflux.
10. Using GHK with PK:PNa = 1:0.04, Vm will be:
A. Exactly EK
B. Close to ENa
C. 0 mV
D. Slightly less negative than EK
Correct Answer: D. Slightly less negative than EK
Rationale: Small Na+ permeability depolarizes slightly.
11. The pump is called electrogenic because it:
A. Moves net positive charge out, slightly hyperpolarizing the cell
B. Generates action potentials
C. Moves no net charge
D. Depolarizes the cell
Correct Answer: A. Moves net positive charge out, slightly hyperpolarizing the cell
Rationale: Contributes a few millivolts.
12. At the resting potential (-70 mV), the net driving force on Na+ is:
A. Outward
B. Zero
C. Weakly outward
D. Strongly inward
Correct Answer: D. Strongly inward
Rationale: Both gradients push Na+ in.
