NPB 101D DISCUSSION QUIZZES QUESTIONS
Quiz 1
1. What would happen to the membrane potential of a cell that is permeable only to
K+ if the permeability of the membrane to that ion suddenly doubled?
a. it would vigorously fire action potentials at a high rate
b. there would be no change
c. it would slowly depolarize
d. it would slowly hyperpolarize- Answers - there would be no change
2. The concentration gradient for Na+ in a normal neuron.
a. favors its movement out of the cell at resting potential.
b. No option is correct
c. favors its movement into the cell at resting potential.
d. Two options are correct
e. is maintained by the Na+-K+ pump.- Answers - Two options are correct
3. Which part of a neuron is responsible for generating action potential?
a.terminal bouton / presynaptic terminal
b. soma/cell body
c. axon hillock
d. dendritic spines- Answers - axon hillock
4. Compared to a neuron at rest, a neuron in the rising phase of an action
potential...
a. has activated voltage gated K+ channels
b. has low permeability to Na+ and high to K+
, c. is at equilibrium
d. has changed its threshold to a more depolarized value
e. has activated many voltage-gated Na+ channels- Answers - has activated many voltage-gated Na+
channelsActivation of voltage-gated K+ channels
5. What is responsible for the fast neuronal repolarization during the falling phase
of the action potential?
a. Activation of voltage-gated K+ channels
b. Opening of the inactivation gate in voltage-gated Na+ channels
c. two options are correct
, d. Inactivation of Na+ leak channels
e. Inactivation of K+ leak channels- Answers - a. Activation of voltage-gated K+ channels
6. The relative refractory period of an action potential is the period during which a neuron
can generate another action potential, but only if the intensity of the stimulus is greater
than normal. Which process is responsible for the relative refractory period of a
neuron?
a. the activation of voltage gated Na+ channels
b. the inactivation of voltage gated Na+ channels
c. the activation of voltage gated K+ channels
d. the inactivation of voltage gated K+ channels- Answers - c. the activation of voltage gated K+
channels
7. Which of the following explains the unidirectional propagation of action
potentials?
A. The voltage dependence of the potassium channels
B. Sufficient "leakiness" of the axons, such that backward propagation of action
potentials is prevented
C. The inactivation of the voltage gated channels
D. The polarized orientation of microtubules within the axon
E. The voltage dependence of the sodium channels- Answers - C. The inactivation of the voltage
gated
channels
8. The Nernst equation considers the concentration, charge and permeability of each
ion.
A. TRUE
B. FALSE- Answers - FALSE
, 9. Curve B- Answers - Which of the following curves corresponds to what happens when one elicits an AP in the
presence
of a drug that blocks VG
K+ channels? Curve C
C
u
r
v
e
E
C
u
r
v
e
B
C
u
r
v
e
A
C
u
Quiz 1
1. What would happen to the membrane potential of a cell that is permeable only to
K+ if the permeability of the membrane to that ion suddenly doubled?
a. it would vigorously fire action potentials at a high rate
b. there would be no change
c. it would slowly depolarize
d. it would slowly hyperpolarize- Answers - there would be no change
2. The concentration gradient for Na+ in a normal neuron.
a. favors its movement out of the cell at resting potential.
b. No option is correct
c. favors its movement into the cell at resting potential.
d. Two options are correct
e. is maintained by the Na+-K+ pump.- Answers - Two options are correct
3. Which part of a neuron is responsible for generating action potential?
a.terminal bouton / presynaptic terminal
b. soma/cell body
c. axon hillock
d. dendritic spines- Answers - axon hillock
4. Compared to a neuron at rest, a neuron in the rising phase of an action
potential...
a. has activated voltage gated K+ channels
b. has low permeability to Na+ and high to K+
, c. is at equilibrium
d. has changed its threshold to a more depolarized value
e. has activated many voltage-gated Na+ channels- Answers - has activated many voltage-gated Na+
channelsActivation of voltage-gated K+ channels
5. What is responsible for the fast neuronal repolarization during the falling phase
of the action potential?
a. Activation of voltage-gated K+ channels
b. Opening of the inactivation gate in voltage-gated Na+ channels
c. two options are correct
, d. Inactivation of Na+ leak channels
e. Inactivation of K+ leak channels- Answers - a. Activation of voltage-gated K+ channels
6. The relative refractory period of an action potential is the period during which a neuron
can generate another action potential, but only if the intensity of the stimulus is greater
than normal. Which process is responsible for the relative refractory period of a
neuron?
a. the activation of voltage gated Na+ channels
b. the inactivation of voltage gated Na+ channels
c. the activation of voltage gated K+ channels
d. the inactivation of voltage gated K+ channels- Answers - c. the activation of voltage gated K+
channels
7. Which of the following explains the unidirectional propagation of action
potentials?
A. The voltage dependence of the potassium channels
B. Sufficient "leakiness" of the axons, such that backward propagation of action
potentials is prevented
C. The inactivation of the voltage gated channels
D. The polarized orientation of microtubules within the axon
E. The voltage dependence of the sodium channels- Answers - C. The inactivation of the voltage
gated
channels
8. The Nernst equation considers the concentration, charge and permeability of each
ion.
A. TRUE
B. FALSE- Answers - FALSE
, 9. Curve B- Answers - Which of the following curves corresponds to what happens when one elicits an AP in the
presence
of a drug that blocks VG
K+ channels? Curve C
C
u
r
v
e
E
C
u
r
v
e
B
C
u
r
v
e
A
C
u
