UTSC NROB61 Neurophysiology: Midterm Exam (Units 1-7) -
Questions with Correct Answers
50 questions
1. Which ion's gradient is most important for the resting potential?
A. Na+
B. Ca2+
C. Mg2+
D. K+
Correct Answer: D. K+
Rationale: Resting membranes are mostly K+-permeable.
2. Which signal decreases in amplitude as it spreads along the membrane?
A. Propagated action potential
B. Graded (local) potential
C. Saltatory action potential
D. Regenerative calcium spike in an axon
Correct Answer: B. Graded (local) potential
Rationale: Graded potentials decay passively.
3. Golgi's silver stain was important because it:
A. Labeled all neurons uniformly
B. Labeled a small fraction of neurons completely
C. Measured membrane potential
D. Recorded action potentials
Correct Answer: B. Labeled a small fraction of neurons completely
Rationale: Sparse labeling revealed individual cell morphology.
4. The resting neuronal membrane is:
A. Positive inside relative to outside
B. At 0 mV
C. Negative inside relative to outside
D. At ENa
Correct Answer: C. Negative inside relative to outside
Rationale: About -65 to -70 mV.
5. The basic direction of information flow in a typical neuron is:
A. Dendrites to soma to axon to terminals
B. Axon to dendrites to soma
C. Terminals to soma to dendrites
D. Soma to dendrites to axon
Correct Answer: A. Dendrites to soma to axon to terminals
Rationale: This is dynamic polarization.
6. The squid giant axon was valuable for classic experiments because:
A. Its large diameter allowed internal electrodes and perfusion
B. It lacks ion channels
C. It has myelin
D. It fires no action potentials
Correct Answer: A. Its large diameter allowed internal electrodes and perfusion
Rationale: Diameter up to about 1 mm.
, 7. The structural and functional properties of neurons are similar across species. This supports:
A. Studying only humans
B. Using model organisms to study general principles
C. Avoiding comparative work
D. That each species uses different ions
Correct Answer: B. Using model organisms to study general principles
Rationale: Principles generalize.
8. Which statement about the action potential is TRUE?
A. Its amplitude grows with stimulus strength
B. It decays exponentially with distance
C. It can summate like EPSPs
D. It propagates without decrement
Correct Answer: D. It propagates without decrement
Rationale: It is regenerated along the axon.
9. If a channel's current reverses at +60 mV, it is most likely selective for:
A. K+
B. Cl-
C. Mixed cations equally
D. Na+
Correct Answer: D. Na+
Rationale: ENa is about +60 mV.
10. N-type (ball-and-chain) inactivation in Shaker K+ channels is caused by:
A. S4 movement only
B. Extracellular toxins
C. An N-terminal peptide that blocks the pore
D. Ca2+ binding
Correct Answer: C. An N-terminal peptide that blocks the pore
Rationale: Removing the ball removes fast inactivation.
11. In a single-channel recording, channel openings appear as:
A. Smooth exponential curves
B. Sine waves
C. Gradual ramps
D. Rectangular steps of fixed amplitude
Correct Answer: D. Rectangular steps of fixed amplitude
Rationale: Channels are either open or closed.
12. Ion channel conductance is measured in:
A. Ohms per volt
B. Farads
C. Siemens (often picosiemens)
D. Coulombs
Correct Answer: C. Siemens (often picosiemens)
Rationale: g = 1/R.
Questions with Correct Answers
50 questions
1. Which ion's gradient is most important for the resting potential?
A. Na+
B. Ca2+
C. Mg2+
D. K+
Correct Answer: D. K+
Rationale: Resting membranes are mostly K+-permeable.
2. Which signal decreases in amplitude as it spreads along the membrane?
A. Propagated action potential
B. Graded (local) potential
C. Saltatory action potential
D. Regenerative calcium spike in an axon
Correct Answer: B. Graded (local) potential
Rationale: Graded potentials decay passively.
3. Golgi's silver stain was important because it:
A. Labeled all neurons uniformly
B. Labeled a small fraction of neurons completely
C. Measured membrane potential
D. Recorded action potentials
Correct Answer: B. Labeled a small fraction of neurons completely
Rationale: Sparse labeling revealed individual cell morphology.
4. The resting neuronal membrane is:
A. Positive inside relative to outside
B. At 0 mV
C. Negative inside relative to outside
D. At ENa
Correct Answer: C. Negative inside relative to outside
Rationale: About -65 to -70 mV.
5. The basic direction of information flow in a typical neuron is:
A. Dendrites to soma to axon to terminals
B. Axon to dendrites to soma
C. Terminals to soma to dendrites
D. Soma to dendrites to axon
Correct Answer: A. Dendrites to soma to axon to terminals
Rationale: This is dynamic polarization.
6. The squid giant axon was valuable for classic experiments because:
A. Its large diameter allowed internal electrodes and perfusion
B. It lacks ion channels
C. It has myelin
D. It fires no action potentials
Correct Answer: A. Its large diameter allowed internal electrodes and perfusion
Rationale: Diameter up to about 1 mm.
, 7. The structural and functional properties of neurons are similar across species. This supports:
A. Studying only humans
B. Using model organisms to study general principles
C. Avoiding comparative work
D. That each species uses different ions
Correct Answer: B. Using model organisms to study general principles
Rationale: Principles generalize.
8. Which statement about the action potential is TRUE?
A. Its amplitude grows with stimulus strength
B. It decays exponentially with distance
C. It can summate like EPSPs
D. It propagates without decrement
Correct Answer: D. It propagates without decrement
Rationale: It is regenerated along the axon.
9. If a channel's current reverses at +60 mV, it is most likely selective for:
A. K+
B. Cl-
C. Mixed cations equally
D. Na+
Correct Answer: D. Na+
Rationale: ENa is about +60 mV.
10. N-type (ball-and-chain) inactivation in Shaker K+ channels is caused by:
A. S4 movement only
B. Extracellular toxins
C. An N-terminal peptide that blocks the pore
D. Ca2+ binding
Correct Answer: C. An N-terminal peptide that blocks the pore
Rationale: Removing the ball removes fast inactivation.
11. In a single-channel recording, channel openings appear as:
A. Smooth exponential curves
B. Sine waves
C. Gradual ramps
D. Rectangular steps of fixed amplitude
Correct Answer: D. Rectangular steps of fixed amplitude
Rationale: Channels are either open or closed.
12. Ion channel conductance is measured in:
A. Ohms per volt
B. Farads
C. Siemens (often picosiemens)
D. Coulombs
Correct Answer: C. Siemens (often picosiemens)
Rationale: g = 1/R.
