NEUROBIOLOGY: PRACTICE EXAM I
QUESTIONS AND ANSWERS
nerve cells are ____ conductors of electricity - Correct Answers -poor
a myelinated neuron has ____ membrane resistance and ____ longitudinal resistance -
Correct Answers -high
low
Which is not a kind of potential exhibited by neurons?
a. reaction
b. action
c. synaptic
d. resting
e. post synaptic - Correct Answers -reaction
electrical signals occurring in nerve cells are cause by ____the cell membrane - Correct
Answers -fluxes of ions across
Which of the following is not required for neurons to communicate? - Correct Answers -
separation of larges amounts of electrical charge, with excess positive charge stored
inside the cell
The transmembrane potential is generated by - Correct Answers -diffusion of ions down
a concentration gradient
T/F
Action potentials are elicited by hyperpolarization. - Correct Answers -FALSE
8. Which of the following statements about electrochemical equilibrium is FALSE?
A. Electrochemical equilibrium involves the movement of a relatively small number of
ions.
B. Ionic gradients are necessary for the generation of the membrane potential.
C. The size of the potential is proportional to the size of the ion gradient.
D. The direction of the ion gradient determines the polarity of the membrane potential.
E. For a given concentration gradient, the resulting potential is independent of the
number of charges on the ion. - Correct Answers -E. For a given concentration gradient,
the resulting potential is independent of the number of charges on the ion.
, Calculate the equilibrium potential for Cl- given an intracellular concentration of 40 mM
and an extracellular contration of 560 mM, as is typical for a squid neuron. - Correct
Answers -C. -0.066 Mv
Which of the following is NOT a class of opioid peptides?
A. dynorphins
B. enkephalins
C. endorphins
D. endocannabinoids - Correct Answers -D. endocannabinoids
Astrocytes help prevent excitotoxicity by taking up glutamate and converting it to
glutamine using the enzyme
A. guanylyl cyclase
C. glutamine synthase
B. glutaminase
D. glutamate translocase - Correct Answers -C. glutamine synthase
if the GABA receptor is ionotropic, it most likely conducts - Correct Answers -Cl-
In a signal transduction cascade using G-proteins and cAMP, which of the following is
NOT a signal amplification step?
A. Activation of G-proteins by an activated receptor
B. Activation of adenylyl cyclase molecules by G-proteins
C. Production of cAMP molecules by adenylyl cyclase
D. Phosphorylation of target proteins by protein kinase A
E. All of the above are steps in which amplification occurs. - Correct Answers -B.
Activation of adenylyl cyclase molecules by G-proteins
action potentials are generated when - Correct Answers -the cell reaches threshold
Why was the voltage clamp critical to the ionic basis of the action potential? - Correct
Answers -because sodium and potassium currents are both time and voltage
dependent, voltage clamping makes it possible to determine how each one contributes
to the action potential
14. Which of the following does NOT stem from the application of Ohm's law to ionic
conductances?
A. The driving force on the ionic current is the difference between the membrane
potential and the ion's Nernst potential.
B. The conductance for an ion is inversely proportional to the resistance of the
membrane to the passage of that ion.
C. All permeant ions experience an identical driving force at each time point during the
course of an action potential.
QUESTIONS AND ANSWERS
nerve cells are ____ conductors of electricity - Correct Answers -poor
a myelinated neuron has ____ membrane resistance and ____ longitudinal resistance -
Correct Answers -high
low
Which is not a kind of potential exhibited by neurons?
a. reaction
b. action
c. synaptic
d. resting
e. post synaptic - Correct Answers -reaction
electrical signals occurring in nerve cells are cause by ____the cell membrane - Correct
Answers -fluxes of ions across
Which of the following is not required for neurons to communicate? - Correct Answers -
separation of larges amounts of electrical charge, with excess positive charge stored
inside the cell
The transmembrane potential is generated by - Correct Answers -diffusion of ions down
a concentration gradient
T/F
Action potentials are elicited by hyperpolarization. - Correct Answers -FALSE
8. Which of the following statements about electrochemical equilibrium is FALSE?
A. Electrochemical equilibrium involves the movement of a relatively small number of
ions.
B. Ionic gradients are necessary for the generation of the membrane potential.
C. The size of the potential is proportional to the size of the ion gradient.
D. The direction of the ion gradient determines the polarity of the membrane potential.
E. For a given concentration gradient, the resulting potential is independent of the
number of charges on the ion. - Correct Answers -E. For a given concentration gradient,
the resulting potential is independent of the number of charges on the ion.
, Calculate the equilibrium potential for Cl- given an intracellular concentration of 40 mM
and an extracellular contration of 560 mM, as is typical for a squid neuron. - Correct
Answers -C. -0.066 Mv
Which of the following is NOT a class of opioid peptides?
A. dynorphins
B. enkephalins
C. endorphins
D. endocannabinoids - Correct Answers -D. endocannabinoids
Astrocytes help prevent excitotoxicity by taking up glutamate and converting it to
glutamine using the enzyme
A. guanylyl cyclase
C. glutamine synthase
B. glutaminase
D. glutamate translocase - Correct Answers -C. glutamine synthase
if the GABA receptor is ionotropic, it most likely conducts - Correct Answers -Cl-
In a signal transduction cascade using G-proteins and cAMP, which of the following is
NOT a signal amplification step?
A. Activation of G-proteins by an activated receptor
B. Activation of adenylyl cyclase molecules by G-proteins
C. Production of cAMP molecules by adenylyl cyclase
D. Phosphorylation of target proteins by protein kinase A
E. All of the above are steps in which amplification occurs. - Correct Answers -B.
Activation of adenylyl cyclase molecules by G-proteins
action potentials are generated when - Correct Answers -the cell reaches threshold
Why was the voltage clamp critical to the ionic basis of the action potential? - Correct
Answers -because sodium and potassium currents are both time and voltage
dependent, voltage clamping makes it possible to determine how each one contributes
to the action potential
14. Which of the following does NOT stem from the application of Ohm's law to ionic
conductances?
A. The driving force on the ionic current is the difference between the membrane
potential and the ion's Nernst potential.
B. The conductance for an ion is inversely proportional to the resistance of the
membrane to the passage of that ion.
C. All permeant ions experience an identical driving force at each time point during the
course of an action potential.
