BIO 251 LATEST 2026 TEST PAPER QUESTIONS AND
ANSWERS GUARANTEE A+
✔✔Which of the following membrane transport mechanisms requires the use of
metabolic energy released from ATP? - ✔✔Both primary and secondary active transport
✔✔In active transport, the affinity (binding strength) of the carrier protein for the
molecule being transported is greater on which side of the membrane? - ✔✔on the side
where the molecule is in lower concentration
✔✔In secondary active transport with sodium, which of the following is FALSE? - ✔✔the
molecule being co-transported with sodium always moves from the side of the
membrane where it has a high concentration to the side where it has a low
concentration
✔✔True or False. The rate at which ions are moved across the membrane by ion
channels is determined by both the concentration gradient for the ion and by the total
number of channels in the membrane. - ✔✔True
✔✔In direct cell-cell communication, ions and small molecules originating within one cell
can diffuse directly into a neighboring cell through________ - ✔✔gap junctions
✔✔For indirect chemical communication between cells, a messenger firsts binds to a
specific _______ on the _______ cell to initiate signal transduction in that cell. -
✔✔receptor: target
✔✔What is the mode of action of a chemical messenger that, when released, enters the
bloodstream to travel to its target cell? - ✔✔Endocrine
✔✔Which of the following will NOT affect the magnitude of a cell's response to a
specific chemical messenger? - ✔✔the size of the messenger
✔✔A cell that is chronically exposed to low levels of a chemical messenger
will_____the receptor population for that chemical messenger on the target cell, often
resulting in hypersensitivity to that messenger. - ✔✔Up regulate
✔✔Communication across a synapse is initiated by the release of a neurotransmitter
from the_______
region of the presynaptic neuron. - ✔✔Axon terminal
✔✔The neurotransmitter that is released from the presynaptic neuron must diffuse
across the_______to reach its receptors on the postsynaptic neuron. - ✔✔Synaptic cleft
, ✔✔What is a molecule that is similar in structure to a chemical messenger and binds
with that messenger's receptor to stimulate a similar response from the target cell? -
✔✔Agonist
✔✔Heroin overdose is usually treated with an opioid________such as naloxone
(Narcan),
which prevents heroin from binding to opiod receptors and reverses the effects of heroin
on the body. - ✔✔Antagonist
✔✔On neuron axons, when voltage-gated potassium (K+) channels open, the
concentration gradient for potassium across the membrane is such that the net
potaasium movement is directed________thereby causing the cell's membrane
potential (Vm) to become more_________ - ✔✔out of the cell : negative
✔✔A change in a cell's membrane potential, such that the inside of the cell becomes
more positive than the resting membrane potential (Vm), is referred to as a______ -
✔✔Depolarization
✔✔Voltage-gated calcium channels in the axon terminals open in direct response to
which of the following? - ✔✔arrival of an action potential at the axon terminal
✔✔On what portion of the neuron do action potentials propagate, i.e., pass along the
membrane? - ✔✔Axon
✔✔The depolarization phase (phase 1) of the action potential is generated by a
rapid_______once threshold is reached. - ✔✔opening of voltage-gated sodium (Na)
channels
✔✔The repolarization phase (phase 2) of action potentials is due primarily to_______ -
✔✔potassium (K*) diffusion out of the cell through open voltage-gated potassium
channels
✔✔During which of the following states of the action potential are the voltage-gated
sodium channels closed and incapable of opening, i.e., "locked?" - ✔✔during the
absolute refractory period
✔✔How can action potentials relay information to the brain about the intensity of a
stimulus, such as distinguishing between a hot and warm skin temperature? - ✔✔due to
the frequency of action potentials generated by sensory neurons that detect
temperature
✔✔True or False. If a hyperpolarizing graded potential arrives at the axon hillock of a
neuron, an action potential will be generated at the hillock. - ✔✔False
ANSWERS GUARANTEE A+
✔✔Which of the following membrane transport mechanisms requires the use of
metabolic energy released from ATP? - ✔✔Both primary and secondary active transport
✔✔In active transport, the affinity (binding strength) of the carrier protein for the
molecule being transported is greater on which side of the membrane? - ✔✔on the side
where the molecule is in lower concentration
✔✔In secondary active transport with sodium, which of the following is FALSE? - ✔✔the
molecule being co-transported with sodium always moves from the side of the
membrane where it has a high concentration to the side where it has a low
concentration
✔✔True or False. The rate at which ions are moved across the membrane by ion
channels is determined by both the concentration gradient for the ion and by the total
number of channels in the membrane. - ✔✔True
✔✔In direct cell-cell communication, ions and small molecules originating within one cell
can diffuse directly into a neighboring cell through________ - ✔✔gap junctions
✔✔For indirect chemical communication between cells, a messenger firsts binds to a
specific _______ on the _______ cell to initiate signal transduction in that cell. -
✔✔receptor: target
✔✔What is the mode of action of a chemical messenger that, when released, enters the
bloodstream to travel to its target cell? - ✔✔Endocrine
✔✔Which of the following will NOT affect the magnitude of a cell's response to a
specific chemical messenger? - ✔✔the size of the messenger
✔✔A cell that is chronically exposed to low levels of a chemical messenger
will_____the receptor population for that chemical messenger on the target cell, often
resulting in hypersensitivity to that messenger. - ✔✔Up regulate
✔✔Communication across a synapse is initiated by the release of a neurotransmitter
from the_______
region of the presynaptic neuron. - ✔✔Axon terminal
✔✔The neurotransmitter that is released from the presynaptic neuron must diffuse
across the_______to reach its receptors on the postsynaptic neuron. - ✔✔Synaptic cleft
, ✔✔What is a molecule that is similar in structure to a chemical messenger and binds
with that messenger's receptor to stimulate a similar response from the target cell? -
✔✔Agonist
✔✔Heroin overdose is usually treated with an opioid________such as naloxone
(Narcan),
which prevents heroin from binding to opiod receptors and reverses the effects of heroin
on the body. - ✔✔Antagonist
✔✔On neuron axons, when voltage-gated potassium (K+) channels open, the
concentration gradient for potassium across the membrane is such that the net
potaasium movement is directed________thereby causing the cell's membrane
potential (Vm) to become more_________ - ✔✔out of the cell : negative
✔✔A change in a cell's membrane potential, such that the inside of the cell becomes
more positive than the resting membrane potential (Vm), is referred to as a______ -
✔✔Depolarization
✔✔Voltage-gated calcium channels in the axon terminals open in direct response to
which of the following? - ✔✔arrival of an action potential at the axon terminal
✔✔On what portion of the neuron do action potentials propagate, i.e., pass along the
membrane? - ✔✔Axon
✔✔The depolarization phase (phase 1) of the action potential is generated by a
rapid_______once threshold is reached. - ✔✔opening of voltage-gated sodium (Na)
channels
✔✔The repolarization phase (phase 2) of action potentials is due primarily to_______ -
✔✔potassium (K*) diffusion out of the cell through open voltage-gated potassium
channels
✔✔During which of the following states of the action potential are the voltage-gated
sodium channels closed and incapable of opening, i.e., "locked?" - ✔✔during the
absolute refractory period
✔✔How can action potentials relay information to the brain about the intensity of a
stimulus, such as distinguishing between a hot and warm skin temperature? - ✔✔due to
the frequency of action potentials generated by sensory neurons that detect
temperature
✔✔True or False. If a hyperpolarizing graded potential arrives at the axon hillock of a
neuron, an action potential will be generated at the hillock. - ✔✔False
