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BIOL 320 Exam 3 Study Guide 2025 – Comprehensive Review, Practice
Questions, and Answer Key for Molecular and Cellular Biology
Prepare for success with the BIOL 320 Exam 3 Study Guide 2025! Access detailed review
notes, practice questions, and answer explanations covering key topics in molecular biology,
genetics, and cellular physiology. Designed to help biology students master exam 3 concepts
with confidence. Perfect for university and online learners seeking verified exam prep materials
and test strategies for BIOL 320.
BIOL 320 Exam 3,
BIOL 320 study guide,
BIOL 320 exam 3 answers,
BIOL 320 practice exam 3,
During an action potential, which of the following actions DOES NOT help return a depolarized
membrane to its resting membrane potential?
(*when I ask a "does not" question, first make a list of all the things that DO help return a depolarized
membrane to its resting membrane potential)
The flow of K+ OUT of the cell
The inactivation of voltage-gated Na+ channels
The opening of voltage-gated K+ channels
The opening of voltage-gated Na+ channels - ANSWER-The opening of voltage-gated Na+ channels
Following excitation in a nerve membrane, the region goes through a brief period during which it cannot
be stimulated again. What takes place during this period?
the membrane potential remains unchanged
ligands bind to voltage-gated Ca2+ channels
voltage-gated Na+ channels in the nerve cell membrane are inactivated
,2|Page
ligand-gated Na+ channels in the nerve cell membrane are inactivated - ANSWER-voltage-gated Na+
channels in the nerve cell membrane are inactivated
What is the role of the Na+-K+ pump in an action potential?
After the action potential, the pump re-establishes the electrochemical gradients of ions
Depolarization is caused by the flow of Na+ through the Na+-K+ pump
Repolarization begins when Na+ flows through the Na+-K+ pump
The Na+-K+ pump triggers the release of neurotransmitters
The Na+-K+ pump is a voltage-gated channel that opens in response to a neurotransmitter - ANSWER-
After the action potential, the pump re-establishes the electrochemical gradients of ions
Tight junctions found between the cells in our intestines PREVENT
Small, non-polar molecules from using simple diffusion to cross the plasma membrane
Membrane proteins from showing lateral movement through the entire plasma membrane of a cell
The formation of a membrane domain
The tethering of proteins in the membrane to proteins in the cytoskeleton
The import of glucose into intestinal cells - ANSWER-Membrane proteins from showing lateral
movement through the entire plasma membrane of a cell
The voltage difference across a membrane is called:
Depolarization
The threshold potential
An action potential
The membrane potential - ANSWER-The membrane potential
What is the difference between channels and transporters?
Only transporters are selective in which solutes they transport
Transporters are much faster at moving solutes than channels
All transporters require ATP hydrolysis, while channels perform passive diffusion
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Transporters move very small solutes, while channels move larger molecules
Only transporters specifically bind to their solutes in a similar manner as an enzyme binds its substrate -
ANSWER-Only transporters specifically bind to their solutes in a similar manner as an enzyme binds its
substrate
If the sodium potassium pump stopped function in the intestinal cells, which of the following would
occur?
The sodium gradient would reach an equilibrium with the intestinal lumen
the sodium inside the cell would decrease in concentration
glucose symport from the intestinal lumen would stop
the high glucose gradient in the cell would decrease - ANSWER-The sodium gradient would reach an
equilibrium with the intestinal lumen
glucose symport from the intestinal lumen would stop
the high glucose gradient in the cell would decrease
Ion channels have different gating mechanisms. Which of the following is NOT an example of how these
mechanisms work?
voltage gated ion channels open in response to a change in water distribution across the membrane
a mechanically gated potassium channel opens in response to physical stimulus
ligand gated ion channels require the binding of a molecule that causes a conformation shift in the
channel protein
voltage gated ion channels can be affected by the concentration gradients of positive or negatively
charged ions - ANSWER-voltage gated ion channels open in response to a change in water distribution
across the membrane
The creation of an action potential on the post synaptic cell is highly regulated. Often several different
neurotransmitters are released in a synapse. A neurotransmitter that is referred to as "inhibitory" means:
it is a chemical that blocks the binding of a ligand
it is a ligand that makes it harder for a post synaptic neuron to reach action potential threshold
it is a competitive inhibitor for excitatory ligand targets
BIOL 320 Exam 3 Study Guide 2025 – Comprehensive Review, Practice
Questions, and Answer Key for Molecular and Cellular Biology
Prepare for success with the BIOL 320 Exam 3 Study Guide 2025! Access detailed review
notes, practice questions, and answer explanations covering key topics in molecular biology,
genetics, and cellular physiology. Designed to help biology students master exam 3 concepts
with confidence. Perfect for university and online learners seeking verified exam prep materials
and test strategies for BIOL 320.
BIOL 320 Exam 3,
BIOL 320 study guide,
BIOL 320 exam 3 answers,
BIOL 320 practice exam 3,
During an action potential, which of the following actions DOES NOT help return a depolarized
membrane to its resting membrane potential?
(*when I ask a "does not" question, first make a list of all the things that DO help return a depolarized
membrane to its resting membrane potential)
The flow of K+ OUT of the cell
The inactivation of voltage-gated Na+ channels
The opening of voltage-gated K+ channels
The opening of voltage-gated Na+ channels - ANSWER-The opening of voltage-gated Na+ channels
Following excitation in a nerve membrane, the region goes through a brief period during which it cannot
be stimulated again. What takes place during this period?
the membrane potential remains unchanged
ligands bind to voltage-gated Ca2+ channels
voltage-gated Na+ channels in the nerve cell membrane are inactivated
,2|Page
ligand-gated Na+ channels in the nerve cell membrane are inactivated - ANSWER-voltage-gated Na+
channels in the nerve cell membrane are inactivated
What is the role of the Na+-K+ pump in an action potential?
After the action potential, the pump re-establishes the electrochemical gradients of ions
Depolarization is caused by the flow of Na+ through the Na+-K+ pump
Repolarization begins when Na+ flows through the Na+-K+ pump
The Na+-K+ pump triggers the release of neurotransmitters
The Na+-K+ pump is a voltage-gated channel that opens in response to a neurotransmitter - ANSWER-
After the action potential, the pump re-establishes the electrochemical gradients of ions
Tight junctions found between the cells in our intestines PREVENT
Small, non-polar molecules from using simple diffusion to cross the plasma membrane
Membrane proteins from showing lateral movement through the entire plasma membrane of a cell
The formation of a membrane domain
The tethering of proteins in the membrane to proteins in the cytoskeleton
The import of glucose into intestinal cells - ANSWER-Membrane proteins from showing lateral
movement through the entire plasma membrane of a cell
The voltage difference across a membrane is called:
Depolarization
The threshold potential
An action potential
The membrane potential - ANSWER-The membrane potential
What is the difference between channels and transporters?
Only transporters are selective in which solutes they transport
Transporters are much faster at moving solutes than channels
All transporters require ATP hydrolysis, while channels perform passive diffusion
, 3|Page
Transporters move very small solutes, while channels move larger molecules
Only transporters specifically bind to their solutes in a similar manner as an enzyme binds its substrate -
ANSWER-Only transporters specifically bind to their solutes in a similar manner as an enzyme binds its
substrate
If the sodium potassium pump stopped function in the intestinal cells, which of the following would
occur?
The sodium gradient would reach an equilibrium with the intestinal lumen
the sodium inside the cell would decrease in concentration
glucose symport from the intestinal lumen would stop
the high glucose gradient in the cell would decrease - ANSWER-The sodium gradient would reach an
equilibrium with the intestinal lumen
glucose symport from the intestinal lumen would stop
the high glucose gradient in the cell would decrease
Ion channels have different gating mechanisms. Which of the following is NOT an example of how these
mechanisms work?
voltage gated ion channels open in response to a change in water distribution across the membrane
a mechanically gated potassium channel opens in response to physical stimulus
ligand gated ion channels require the binding of a molecule that causes a conformation shift in the
channel protein
voltage gated ion channels can be affected by the concentration gradients of positive or negatively
charged ions - ANSWER-voltage gated ion channels open in response to a change in water distribution
across the membrane
The creation of an action potential on the post synaptic cell is highly regulated. Often several different
neurotransmitters are released in a synapse. A neurotransmitter that is referred to as "inhibitory" means:
it is a chemical that blocks the binding of a ligand
it is a ligand that makes it harder for a post synaptic neuron to reach action potential threshold
it is a competitive inhibitor for excitatory ligand targets
