©SIRJOEL EXAM SOLUTIONS
12/3/2024 11:27AM
CBN Exam II Questions With Correct
Answers
The resting membrane potential is closer to the equilibrium potential for _______ than the
equilibrium potential for ________ . This is because ________________. - answer✔potassium ;
sodium ; at rest the membrane has mostly potassium channels open
If all you know about an ion is that the concentration of this ion is higher inside the cell than
outside it, and that the ion has a positive charge. Would you be able to make any predictions
about the equilibrium potential for this ion? - answer✔The equilibrium potential is negative
Consider a neuron in which the intracellular fluid has a potassium concentration of 100 mM, and
the extracellular fluid has a potassium concentration of 1 mM. If the cell membrane is permeable
only to potassium ions, what is the voltage across the membrane? [assume that the system is at
equilibrium and at body temperature; log 100 = 2, log 10 = 1; log 1 = 0; log 0.1 = -1; log 0.01 = -
2] - answer✔-124 mV
A voltage-gated sodium channel: - answer✔contains four helical transmembrane regions with
positively charged amino acids that serve as the voltage sensor
, ©SIRJOEL EXAM SOLUTIONS
12/3/2024 11:27AM
How do action potentials differ from passively conducted electrical signals, such as EPSPs? -
answer✔Action potentials are signals of fixed size and duration; passively conducted signals are
not a fixed size and duration.
What role do voltage-gated potassium channels play in the action potential? - answer✔Voltage-
gated potassium channels help restore a negative membrane potential after the peak of the action
potential.
What are some of the similarities and differences between leak channels and voltage-gated
potassium channels? - answer✔Leak channels and voltage-gated potassium channels are both
permeable to potassium ions
According to the model of voltage-gated sodium channels, there is no current through the
channel during the end of a prolonged depolarizing voltage pulse to -40 mV or above because
__________________ - answer✔a globular part of the channel is blocking the pore.
Approximately how long does an action potential last from the beginning of the rising phase to
the end of the falling phase? - answer✔1 millisecond
Human brain is a variation of common structures found in _____ - answer✔many mammalian
brains
Cortical tissue - answer✔allows for higher human function like thinking and planning
12/3/2024 11:27AM
CBN Exam II Questions With Correct
Answers
The resting membrane potential is closer to the equilibrium potential for _______ than the
equilibrium potential for ________ . This is because ________________. - answer✔potassium ;
sodium ; at rest the membrane has mostly potassium channels open
If all you know about an ion is that the concentration of this ion is higher inside the cell than
outside it, and that the ion has a positive charge. Would you be able to make any predictions
about the equilibrium potential for this ion? - answer✔The equilibrium potential is negative
Consider a neuron in which the intracellular fluid has a potassium concentration of 100 mM, and
the extracellular fluid has a potassium concentration of 1 mM. If the cell membrane is permeable
only to potassium ions, what is the voltage across the membrane? [assume that the system is at
equilibrium and at body temperature; log 100 = 2, log 10 = 1; log 1 = 0; log 0.1 = -1; log 0.01 = -
2] - answer✔-124 mV
A voltage-gated sodium channel: - answer✔contains four helical transmembrane regions with
positively charged amino acids that serve as the voltage sensor
, ©SIRJOEL EXAM SOLUTIONS
12/3/2024 11:27AM
How do action potentials differ from passively conducted electrical signals, such as EPSPs? -
answer✔Action potentials are signals of fixed size and duration; passively conducted signals are
not a fixed size and duration.
What role do voltage-gated potassium channels play in the action potential? - answer✔Voltage-
gated potassium channels help restore a negative membrane potential after the peak of the action
potential.
What are some of the similarities and differences between leak channels and voltage-gated
potassium channels? - answer✔Leak channels and voltage-gated potassium channels are both
permeable to potassium ions
According to the model of voltage-gated sodium channels, there is no current through the
channel during the end of a prolonged depolarizing voltage pulse to -40 mV or above because
__________________ - answer✔a globular part of the channel is blocking the pore.
Approximately how long does an action potential last from the beginning of the rising phase to
the end of the falling phase? - answer✔1 millisecond
Human brain is a variation of common structures found in _____ - answer✔many mammalian
brains
Cortical tissue - answer✔allows for higher human function like thinking and planning
