BIOL 3701 Exam I Practice Questions
Hypokalemia (decreased blood K+ concentration) will
a. increase cell sensitivity by moving resting membrane potential closer to threshold
b. increase cell sensitivity by moving resting membrane potential farther from threshold
c. decrease cell sensitivity by moving resting membrane potential closer to threshold
d. decrease cell sensitivity by moving resting membrane potential farther from threshold
e. not change cell sensitivity as it will not change resting membrane potential - correct answer
(d) because there is less K+ to depolarize the membrane and lower potassium levels in the ECF cause the
membrane potential to hyper-polarize, meaning that a larger stimulus is needed to generate an action
potential
If you place two electrodes at either end of an axon (proximally near the hillock and distally near the
nerve terminal) and artificially depolarize the cell membrane above threshold in both locations at once,
resulting action potential(s) will
a. not result as there is no mechanism to activate a cell with electrical charge
b. migrate from the hillock toward the nerve terminal and from the nerve terminal toward the hillock
until they meet
c. not occur as they will cancel each other out
d. only migrate from the hillock towards the nerve terminal as this is anatomically the way it is supposed
to travel
,e. migrate from the hillock to the cell body and are from the nerve terminal to the pre-synaptic
membrane - correct answer b. because you are stimulating both the afferent and
efferent neurons
The following solution is given to a patient: 100mM NaCl and 100 mOsm of urea. This solution is _____,
and ______, and will cause the cell to _______. - correct answer
If one inhibits ATP production, which transport mechanism(s) will NOT be affected
a. primary active transport
b. secondary active transport
c. facilitated diffusion
d. simple diffusion
e. both C and D are correct - correct answer e because both simple and facilitated
diffusion do not require ATP to take place
If ATP were eliminated from the pathway shown, the net effect would be
a. the concentration of Na+ would shift to being similar across all 3 regions
b. intracellular Na+ would increase
c. intracellular Na+ would decreasse
d. uptake of Na+ from the lumen to the blood would increase - correct answer c
because
In a neuro lab, you partner says they recorded a resting membrane potential of -50mV in a nerve
preparation. In response you tell them (as a viable explanation)
, a. this is not possible under normal physiological conditions
b. the ringers solution must have been made with too little potassium
c. the ringer solution must have been made with too much potassium
d. A and B are correct
e. A and C are correct - correct answer c because the more positive the resting
membrane potential is, the more K+ must be present
Suppose the gene encoding the potassium leak channel has a mutation that slightly increases the
efficiency of the channel. What would be the predicted effect of the mutation on membrane potential?
Assume the effect is nonlethal.
a. it will hyperpolarize the membrane potential
b. it will depolarize the membrane potential
c. it will have no effect on membrane potential
d. it dissipates membrane potential - correct answer a because the potassium leak
channels are bringing potassium out of the cell and when the efficiency is increased, but not bringing
sodium into the cell, so the membrane potential will hyperpolarize and not depolarize
Using [Na+i] =15mM and [Na+o]= 145 mM, gives ENa =60mV. If the cell is freely permeable to Na+ the
direction of flux would be in the direction (in, out, equilibrium) for each of the following Vm? 0, 60, and
70.
a. in, in, out
b. in, equilibrium, in
Hypokalemia (decreased blood K+ concentration) will
a. increase cell sensitivity by moving resting membrane potential closer to threshold
b. increase cell sensitivity by moving resting membrane potential farther from threshold
c. decrease cell sensitivity by moving resting membrane potential closer to threshold
d. decrease cell sensitivity by moving resting membrane potential farther from threshold
e. not change cell sensitivity as it will not change resting membrane potential - correct answer
(d) because there is less K+ to depolarize the membrane and lower potassium levels in the ECF cause the
membrane potential to hyper-polarize, meaning that a larger stimulus is needed to generate an action
potential
If you place two electrodes at either end of an axon (proximally near the hillock and distally near the
nerve terminal) and artificially depolarize the cell membrane above threshold in both locations at once,
resulting action potential(s) will
a. not result as there is no mechanism to activate a cell with electrical charge
b. migrate from the hillock toward the nerve terminal and from the nerve terminal toward the hillock
until they meet
c. not occur as they will cancel each other out
d. only migrate from the hillock towards the nerve terminal as this is anatomically the way it is supposed
to travel
,e. migrate from the hillock to the cell body and are from the nerve terminal to the pre-synaptic
membrane - correct answer b. because you are stimulating both the afferent and
efferent neurons
The following solution is given to a patient: 100mM NaCl and 100 mOsm of urea. This solution is _____,
and ______, and will cause the cell to _______. - correct answer
If one inhibits ATP production, which transport mechanism(s) will NOT be affected
a. primary active transport
b. secondary active transport
c. facilitated diffusion
d. simple diffusion
e. both C and D are correct - correct answer e because both simple and facilitated
diffusion do not require ATP to take place
If ATP were eliminated from the pathway shown, the net effect would be
a. the concentration of Na+ would shift to being similar across all 3 regions
b. intracellular Na+ would increase
c. intracellular Na+ would decreasse
d. uptake of Na+ from the lumen to the blood would increase - correct answer c
because
In a neuro lab, you partner says they recorded a resting membrane potential of -50mV in a nerve
preparation. In response you tell them (as a viable explanation)
, a. this is not possible under normal physiological conditions
b. the ringers solution must have been made with too little potassium
c. the ringer solution must have been made with too much potassium
d. A and B are correct
e. A and C are correct - correct answer c because the more positive the resting
membrane potential is, the more K+ must be present
Suppose the gene encoding the potassium leak channel has a mutation that slightly increases the
efficiency of the channel. What would be the predicted effect of the mutation on membrane potential?
Assume the effect is nonlethal.
a. it will hyperpolarize the membrane potential
b. it will depolarize the membrane potential
c. it will have no effect on membrane potential
d. it dissipates membrane potential - correct answer a because the potassium leak
channels are bringing potassium out of the cell and when the efficiency is increased, but not bringing
sodium into the cell, so the membrane potential will hyperpolarize and not depolarize
Using [Na+i] =15mM and [Na+o]= 145 mM, gives ENa =60mV. If the cell is freely permeable to Na+ the
direction of flux would be in the direction (in, out, equilibrium) for each of the following Vm? 0, 60, and
70.
a. in, in, out
b. in, equilibrium, in
