BIPN 100 FINAL questions with
verified answers passed
For the sodium-glucose transporter (SGLT), glucose binds the receptor despite the low
concentration of glucose in the extracellular space. This is because the:
A) SGLT directly uses ATP to allow glucose to bind and be transported across the plasma
membrane.
B) SGLT first binds sodium, which causes a conformational change that reveals a high affinity
glucose binding site.
C) SGLT is a coincidence detector that allows glucose to bind when there is an appropriate
ligand and depolarization of the plasma membrane.
D) SGLT binds glucose when the concentration gradient of sodium is reversed by repetitive
action potential firing.
E) None of the above. - correct answer ✔✔B) SGLT first binds sodium, which causes a
conformational change that reveals a high affinity glucose binding site.
Which of the following is true regarding the sodium-potassium pump (Na-K pump)?
A) One cycle of this transporter moves 3 ions of potassium into the cell and 2 sodium out.
B) The Na-K pump indirectly uses ATP by exploiting the potential energy provided by the sodium
concentration gradient.
C) The Na-K pump decreases sodium and potassium concentration gradients across the plasma
membrane.
D) The Na-K pump establishes an electrical gradient between the intracellular and extracellular
compartments.
E) The Na-K pump can also transport chloride ions if there is no sodium available. - correct
answer ✔✔D) The Na-K pump establishes an electrical gradient between the intracellular and
extracellular compartments.
,If a cell's membrane contains unusually high numbers of sodium-permeable leak channels, what
effect would this have on the cell's resting membrane potential?
A) The resting membrane potential would be less negative.
B) The resting membrane potential would be more negative.
C) The resting membrane potential would be unchanged.
D) The resting membrane potential would oscillate due to sodium channel inactivation.
E) None of the above. - correct answer ✔✔A) The resting membrane potential would be less
negative.
If a GPCR is activated and Gαi signaling is initiated, what will happen?
A) Calcium will be released from the ER
B) More cAMP will be produced
C) Calcium will enter the cell through Gαi gated calcium channels
D) Less PKC will be activated
E) Less PKA will be activated - correct answer ✔✔E) Less PKA will be activated
A mutation is introduced into a voltage-gated sodium channel that causes it to be in the
inactivated state for a longer period of time. How would this affect the action potential?
A) The action potential will be broader (longer duration)
B) The action potential will be narrower (shorter duration)
C) The peak amplitude of the action potential will be more positive
D) The action potential will have a longer absolute refractory period
E) The action potential will have a shorter absolute refractory period - correct answer ✔✔D)
The action potential will have a longer absolute refractory period
If a stimulating electrode is placed in the middle of an axon at rest and a sub-threshold voltage
is applied to axon through the electrode, action potentials will
A) not be generated
, B) start at that point and proceed only toward the axon terminal
C) start at that point and proceed only toward the cell body
D) start at that point and travel in both directions in the axon
E) will be generated but will not propagate along the axon. - correct answer ✔✔A) not be
generated
If voltage-gated calcium channels were absent from the presynaptic axon terminal, how would
this affect synaptic transmission?
A) The clear synaptic vesicles would be less effectively filled.
B) The SNARE complex would be longer in duration.
C) The action potential would be longer in duration.
D) The action potential could not trigger synaptic vesicle fusion.
E) The postsynaptic depolarization would be larger. - correct answer ✔✔D) The action potential
could not trigger synaptic vesicle fusion.
Which of the following is true for both botulinum and tetanus toxin?
A) Both toxins disrupt the function of transporters involved in filling synaptic vesicles.
B) Both toxins cleave proteins that are part of the SNARE complex preventing the fusion of
synaptic vesicles.
C) Both toxins lead to elevated levels of cAMP.
D) Both toxins perturb GTP → GDP cycling on the alpha subunit of a G-protein.
E) Both toxins act at the neuromuscular junction. - correct answer ✔✔B) Both toxins cleave
proteins that are part of the SNARE complex preventing the fusion of synaptic vesicles.
NMDA receptors require postsynaptic depolarization in order to conduct ions. This is because
the depolarization
A) Relieves magnesium block of the receptor
B) Brings the membrane potential further from the potassium equilibrium potential
verified answers passed
For the sodium-glucose transporter (SGLT), glucose binds the receptor despite the low
concentration of glucose in the extracellular space. This is because the:
A) SGLT directly uses ATP to allow glucose to bind and be transported across the plasma
membrane.
B) SGLT first binds sodium, which causes a conformational change that reveals a high affinity
glucose binding site.
C) SGLT is a coincidence detector that allows glucose to bind when there is an appropriate
ligand and depolarization of the plasma membrane.
D) SGLT binds glucose when the concentration gradient of sodium is reversed by repetitive
action potential firing.
E) None of the above. - correct answer ✔✔B) SGLT first binds sodium, which causes a
conformational change that reveals a high affinity glucose binding site.
Which of the following is true regarding the sodium-potassium pump (Na-K pump)?
A) One cycle of this transporter moves 3 ions of potassium into the cell and 2 sodium out.
B) The Na-K pump indirectly uses ATP by exploiting the potential energy provided by the sodium
concentration gradient.
C) The Na-K pump decreases sodium and potassium concentration gradients across the plasma
membrane.
D) The Na-K pump establishes an electrical gradient between the intracellular and extracellular
compartments.
E) The Na-K pump can also transport chloride ions if there is no sodium available. - correct
answer ✔✔D) The Na-K pump establishes an electrical gradient between the intracellular and
extracellular compartments.
,If a cell's membrane contains unusually high numbers of sodium-permeable leak channels, what
effect would this have on the cell's resting membrane potential?
A) The resting membrane potential would be less negative.
B) The resting membrane potential would be more negative.
C) The resting membrane potential would be unchanged.
D) The resting membrane potential would oscillate due to sodium channel inactivation.
E) None of the above. - correct answer ✔✔A) The resting membrane potential would be less
negative.
If a GPCR is activated and Gαi signaling is initiated, what will happen?
A) Calcium will be released from the ER
B) More cAMP will be produced
C) Calcium will enter the cell through Gαi gated calcium channels
D) Less PKC will be activated
E) Less PKA will be activated - correct answer ✔✔E) Less PKA will be activated
A mutation is introduced into a voltage-gated sodium channel that causes it to be in the
inactivated state for a longer period of time. How would this affect the action potential?
A) The action potential will be broader (longer duration)
B) The action potential will be narrower (shorter duration)
C) The peak amplitude of the action potential will be more positive
D) The action potential will have a longer absolute refractory period
E) The action potential will have a shorter absolute refractory period - correct answer ✔✔D)
The action potential will have a longer absolute refractory period
If a stimulating electrode is placed in the middle of an axon at rest and a sub-threshold voltage
is applied to axon through the electrode, action potentials will
A) not be generated
, B) start at that point and proceed only toward the axon terminal
C) start at that point and proceed only toward the cell body
D) start at that point and travel in both directions in the axon
E) will be generated but will not propagate along the axon. - correct answer ✔✔A) not be
generated
If voltage-gated calcium channels were absent from the presynaptic axon terminal, how would
this affect synaptic transmission?
A) The clear synaptic vesicles would be less effectively filled.
B) The SNARE complex would be longer in duration.
C) The action potential would be longer in duration.
D) The action potential could not trigger synaptic vesicle fusion.
E) The postsynaptic depolarization would be larger. - correct answer ✔✔D) The action potential
could not trigger synaptic vesicle fusion.
Which of the following is true for both botulinum and tetanus toxin?
A) Both toxins disrupt the function of transporters involved in filling synaptic vesicles.
B) Both toxins cleave proteins that are part of the SNARE complex preventing the fusion of
synaptic vesicles.
C) Both toxins lead to elevated levels of cAMP.
D) Both toxins perturb GTP → GDP cycling on the alpha subunit of a G-protein.
E) Both toxins act at the neuromuscular junction. - correct answer ✔✔B) Both toxins cleave
proteins that are part of the SNARE complex preventing the fusion of synaptic vesicles.
NMDA receptors require postsynaptic depolarization in order to conduct ions. This is because
the depolarization
A) Relieves magnesium block of the receptor
B) Brings the membrane potential further from the potassium equilibrium potential
