Bio 137 Nervous System Exam Actual Exam 2026 || Most Recent Exam
2026|2027 Actual Complete Real Exam Questions And Correct
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A neuron is exposed to a chemical that keeps voltage gated sodium
channels open far longer than normal. Which change would occur first?
-ANSWER- Prolonged depolarization
A membrane potential changes from −70 mV to −55 mV and then
immediately returns toward −70 mV without reaching threshold. What
does this demonstrate? -ANSWER- A subthreshold graded potential
Increasing the intensity of a stimulus produces larger graded potentials
but does not increase the amplitude of individual action potentials.
What principle explains this difference? -ANSWER- Graded potentials
vary in magnitude, whereas action potentials are all or none
An axon is completely myelinated except for its nodes. If the nodes
become electrically nonfunctional, which event is disrupted? -ANSWER-
Regeneration of the action potential during saltatory conduction
A neuron reaches threshold at the axon hillock, but voltage gated
sodium channels are experimentally blocked. What should happen? -
ANSWER- The action potential cannot be initiated normally
,During an action potential, sodium permeability rises sharply and then
falls while potassium permeability rises. Which sequence is
represented? -ANSWER- Depolarization followed by repolarization
A membrane becomes temporarily more negative than its resting
potential immediately after repolarization. What explains this change? -
ANSWER- Continued potassium efflux during the relative refractory
period
A neuron receives five excitatory inputs simultaneously from different
presynaptic neurons. None reaches threshold alone, but together they
do. What principle is being demonstrated? -ANSWER- Spatial
summation
One presynaptic neuron repeatedly releases excitatory
neurotransmitter at very short intervals. The resulting potentials
accumulate until threshold is reached. What principle is demonstrated?
-ANSWER- Temporal summation
A synapse releases normal amounts of neurotransmitter, but the
postsynaptic membrane has no functional receptors for it. Where is the
major defect? -ANSWER- Postsynaptic reception
An action potential reaches an axon terminal, but calcium channels
there cannot open. Which event is most directly prevented? -ANSWER-
Neurotransmitter release
, A drug prevents synaptic vesicles from fusing with the presynaptic
membrane. Which step has been interrupted? -ANSWER- Exocytosis of
neurotransmitter
A neurotransmitter remains in the synaptic cleft because its normal
degrading enzyme has been inhibited. What would most likely happen?
-ANSWER- The neurotransmitter's effect would persist longer
A neurotransmitter produces an IPSP. Which membrane change would
make another action potential less likely? -ANSWER- Hyperpolarization
Two postsynaptic neurons receive identical excitatory
neurotransmitters. One reaches threshold and the other does not.
Which factor could explain the difference? -ANSWER- The second
neuron received stronger inhibitory input
A neuron receives simultaneous excitatory and inhibitory signals.
Where is the combined effect most important for determining whether
an action potential begins? -ANSWER- Axon hillock and initial segment
A mutation prevents the sodium potassium pump from functioning for
an extended period. Which consequence is most likely after repeated
neural activity? -ANSWER- Ion concentration gradients gradually
deteriorate
2026|2027 Actual Complete Real Exam Questions And Correct
Answers (Verified Answers) Already Graded A+ | Guaranteed
Success!! Newest Exam | Just Released!!
A neuron is exposed to a chemical that keeps voltage gated sodium
channels open far longer than normal. Which change would occur first?
-ANSWER- Prolonged depolarization
A membrane potential changes from −70 mV to −55 mV and then
immediately returns toward −70 mV without reaching threshold. What
does this demonstrate? -ANSWER- A subthreshold graded potential
Increasing the intensity of a stimulus produces larger graded potentials
but does not increase the amplitude of individual action potentials.
What principle explains this difference? -ANSWER- Graded potentials
vary in magnitude, whereas action potentials are all or none
An axon is completely myelinated except for its nodes. If the nodes
become electrically nonfunctional, which event is disrupted? -ANSWER-
Regeneration of the action potential during saltatory conduction
A neuron reaches threshold at the axon hillock, but voltage gated
sodium channels are experimentally blocked. What should happen? -
ANSWER- The action potential cannot be initiated normally
,During an action potential, sodium permeability rises sharply and then
falls while potassium permeability rises. Which sequence is
represented? -ANSWER- Depolarization followed by repolarization
A membrane becomes temporarily more negative than its resting
potential immediately after repolarization. What explains this change? -
ANSWER- Continued potassium efflux during the relative refractory
period
A neuron receives five excitatory inputs simultaneously from different
presynaptic neurons. None reaches threshold alone, but together they
do. What principle is being demonstrated? -ANSWER- Spatial
summation
One presynaptic neuron repeatedly releases excitatory
neurotransmitter at very short intervals. The resulting potentials
accumulate until threshold is reached. What principle is demonstrated?
-ANSWER- Temporal summation
A synapse releases normal amounts of neurotransmitter, but the
postsynaptic membrane has no functional receptors for it. Where is the
major defect? -ANSWER- Postsynaptic reception
An action potential reaches an axon terminal, but calcium channels
there cannot open. Which event is most directly prevented? -ANSWER-
Neurotransmitter release
, A drug prevents synaptic vesicles from fusing with the presynaptic
membrane. Which step has been interrupted? -ANSWER- Exocytosis of
neurotransmitter
A neurotransmitter remains in the synaptic cleft because its normal
degrading enzyme has been inhibited. What would most likely happen?
-ANSWER- The neurotransmitter's effect would persist longer
A neurotransmitter produces an IPSP. Which membrane change would
make another action potential less likely? -ANSWER- Hyperpolarization
Two postsynaptic neurons receive identical excitatory
neurotransmitters. One reaches threshold and the other does not.
Which factor could explain the difference? -ANSWER- The second
neuron received stronger inhibitory input
A neuron receives simultaneous excitatory and inhibitory signals.
Where is the combined effect most important for determining whether
an action potential begins? -ANSWER- Axon hillock and initial segment
A mutation prevents the sodium potassium pump from functioning for
an extended period. Which consequence is most likely after repeated
neural activity? -ANSWER- Ion concentration gradients gradually
deteriorate
