Worksheetsbio basis of behaviour 4
Total questions: 100
Worksheet time: 50mins
What is the effect of chloride channels opening in a neuron?
Chloride influx
Potassium efflux
Sodium influx
Calcium efflux
Where does action potential initiation typically occur in a neuron?
Axon hillock/initial segment
Dendritic spine
Cell body membrane
Synaptic cleft
Which of the following is true about EPSPs and IPSPs?
They last only a few milliseconds before decaying.
They last for several minutes.
They are permanent changes.
They only occur in the axon.
Why can't action potentials be generated at the cell body membrane?
It lacks voltage-activated channels.
It has too many synapses.
It is too far from the axon.
It is always hyperpolarized.
What is temporal summation in neurons?
Two EPSPs in quick succession can add together.
EPSPs and IPSPs from different synapses combine.
Action potentials are generated at the dendrite.
Neurotransmitters are released in the synaptic cleft.
If two excitatory pulses occur simultaneously, what is the result?
They sum fully, forming one large EPSP.
They cancel each other out.
They form two independent EPSPs.
They produce a smaller depolarization.
How does the size of a graded potential relate to stimulation?
It is proportional to the intensity of stimulation.
It is always the same size.
It is inversely proportional to stimulation.
It does not depend on stimulation.
What is the net result of summation in neurons?
It determines whether threshold is reached at the axon hillock.
It always causes an action potential.
It only affects the dendrites.
It inhibits neurotransmitter release.
Which of the following best describes temporal summation?
It is a property of only EPSPs.
It is a property of only IPSPs.
It is a property of both EPSPs and IPSPs.
It does not occur in postsynaptic potentials.
What is required for spatial summation to occur?
Proximity in both location and timing.
Only timing proximity.
Only location proximity.
No proximity is required.
Which ion movement is associated with EPSPs during summation?
Na+ influx
Cl- influx
K+ efflux
Ca2+ influx
If two EPSPs occur at the same time but far apart on the membrane, what is the result?
They sum into a larger EPSP.
They do not interact.
They cause hyperpolarization.
They result in an IPSP.
Which of the following statements about IPSPs is correct?
IPSPs only involve Na+ influx.
IPSPs involve either Cl- influx or K+ efflux.
IPSPs require only timing proximity for summation.
IPSPs cannot sum together.
A student observes that two inhibitory postsynaptic potentials (IPSPs) occur close together in both space and time. What is the expected outcome?
They remain as two separate IPSPs.
They sum into a larger hyperpolarization.
They convert into EPSPs.
No change occurs.
Why does no summation occur when postsynaptic potentials are far apart in time or space?
Ion movements cancel each other out.
Ion movements do not add together.
Only EPSPs are present.
Only IPSPs are present.
Which of the following best explains the role of ions in summation?
Summation is unrelated to ion flows.
Summation is fundamentally the summation of ion flows.
Only EPSPs involve ion flows.
Only IPSPs involve ion flows.
Which of the following best describes what happens when Na⁺ influx (EPSP) and Cl⁻ influx or K⁺ efflux (IPSP) occur close together in time and space?
The effects cancel each other out completely.
The net effect is recorded as the difference between the two.
Only the EPSP is recorded.
Only the IPSP is recorded.
Where does the final integration of incoming signals in a neuron occur?
Dendritic spine
Axon terminal
Axon initial segment (axon hillock)
Soma
What is the defining characteristic of an action potential in terms of membrane polarity?
Small, local change in membrane voltage
Brief but very large reversal in axon membrane polarity
Gradual increase in membrane potential
Constant, unchanging membrane potential
How long does an action potential typically last?
About 10 ms
About 1 ms
About 100 ms
About 0.1 ms
Which of the following statements about action potentials is TRUE?
They are graded, local changes in membrane voltage.
They are all-or-none, large voltage reversals.
They only occur in dendrites.
They last several seconds.
What causes the depolarizing phase of the action potential?
K⁺ efflux
Na⁺ influx
Cl⁻ influx
Ca²⁺ influx
Which phase of the action potential is caused by K⁺ efflux?
Depolarizing phase
Resting phase
Hyperpolarizing/repolarizing phase
Threshold phase
Why can hundreds of action potentials occur within one second?
Because action potentials are slow and sustained
Because action potentials are brief
Because action potentials only occur in the soma
Because action potentials do not require ions
Contrast graded potentials and action potentials in terms of their effect on membrane voltage.
Graded potentials are all-or-none; action potentials are local.
Graded potentials are large voltage reversals; action potentials are small changes.
Graded potentials are local, small changes; action potentials are all-or-none, large voltage reversals.
Both are all-or-none, large voltage reversals.
A neuron sums all incoming signals that are close together in time and space. What is the significance of this process?
It allows the neuron to ignore all inhibitory signals.
It ensures that only one type of signal is processed at a time.
It represents the combined influence of all EPSPs and IPSPs on the cell body membrane.
It prevents the initiation of action potentials.
What is the approximate value of the threshold potential that triggers rapid membrane depolarization?
-70 mV
+30 mV
-50 mV
0 mV
Which direction does the membrane potential move toward during rapid depolarization after reaching the threshold potential?
Toward -70 mV
Toward 0 mV and overshoots to about +30 mV
Toward -90 mV
Toward -50 mV
What is the net voltage change during an action potential?
~50 mV swing in both directions
~70 mV swing in both directions
~100 mV swing in both directions
~30 mV swing in both directions
What is the effect of TEA (tetraethylammonium) on ion channels?
Blocks sodium channels
Blocks potassium channels
Opens calcium channels
Blocks chloride channels
What is the main conclusion from experiments using TEA and TTX regarding action potentials?
Action potentials depend only on sodium ion flows
Action potentials depend only on potassium ion flows
Action potentials depend on both sodium and potassium ion flows
Action potentials do not depend on ion flows
What happens to voltage-activated sodium channels when the threshold is reached?
They remain closed
They open slowly
They open quickly, allowing rapid Na⁺ influx
They allow rapid K⁺ influx
Which of the following best describes the state of ion channels during the resting state?
Channels are open
Channels are closed
Only sodium channels are open
Only potassium channels are open
TEA and TTX are used in experiments to block which types of channels, respectively?
TEA blocks sodium channels, TTX blocks potassium channels
TEA blocks potassium channels, TTX blocks sodium channels
Both block sodium channels
Both block potassium channels
What is the function of the first gate in voltage-activated sodium channels?
Opens slowly during repolarization
Opens fast during depolarization
Closes the channel permanently
Allows potassium influx
At what membrane potential does the second gate of the sodium channel close (inactivation) during an action potential?
-70 mV
0 mV
+30 mV
-50 mV
Which of the following statements about voltage-activated potassium channels is correct?
They open more quickly than sodium channels.
They open more slowly than sodium channels.
They close before sodium channels.
They do not contribute to repolarization.
What is the main result of potassium channel opening during an action potential?
Depolarization only
Repolarization and hyperpolarization
Inhibition of action potentials
Sodium influx
Which part of the neuron is rich in voltage-activated channels and serves as the trigger zone for action potentials?
Dendrites
Soma
Axon/initial segment (axon hillock)
Synaptic terminal
Why are inputs closer to the initial segment (axon hillock) more influential than distant inputs?
They are always excitatory.
They are less likely to be regulated.
They have a greater effect on action potential initiation.
They are not affected by IPSPs.
What happens if the threshold at the initial segment is reached only briefly?
No action potentials occur.
A rapid succession of action potentials occurs.
Only a few action potentials occur.
The neuron becomes hyperpolarized.
Which of the following is true about Giant Depolarizing Potentials (GDPs)?
They are seen in mature neurons only.
They occur when neurons are normally refractory.
They inhibit neural circuitry development.
They are only found in the spinal cord.
What is the believed function of Giant Depolarizing Potentials (GDPs) in developing hippocampal cells?
To inhibit synaptic transmission
To shape neural circuitry during brain development
To prevent action potentials
To increase potassium efflux
What is back propagation in the context of neuronal activity?
The reverse movement of an action potential from the initial segment into dendrites.
The forward movement of an action potential from dendrites to the axon terminal.
The process of neurotransmitter release at the synapse.
The inhibition of synaptic transmission.
Which of the following is a possible function of back propagation in neurons?
Signals dendrites that the neuron has fired.
Increases the speed of neurotransmitter release.
Prevents the formation of dendritic branches.
Decreases the number of ion channels.
Some nonmammalian neurons are unique because they:
Lack dendritic branches.
Have more axons than dendrites.
Do not contain ion channels.
Are unable to generate action potentials.
Which statement best describes the role of nervous system adaptation in species-specific behaviors?
Nervous systems adapt structural and functional modifications for species-specific behaviors.
Nervous systems remain unchanged across all species.
Nervous systems only adapt structurally, not functionally.
Nervous systems adapt only in response to injury.
What is the main principle behind optogenetics?
Combining genetics and light to control targeted cells in living tissue.
Using only electrical stimulation to activate neurons.
Applying chemical signals to control gene expression.
Using sound waves to manipulate neural activity.
Which method is used in optogenetics to control neurons?
Inserting light-sensitive ion channels into neurons using transgenic techniques.
Applying heat to neurons to change their activity.
Using magnetic fields to alter neural function.
Injecting neurotransmitters directly into the brain.
Channelrhodopsin-2 (ChR2) is found in which organism?
Green alga Chlamydomonas reinhardtii
Fruit fly Drosophila melanogaster
Mouse Mus musculus
Baker’s yeast Saccharomyces cerevisiae
What happens when Channelrhodopsin-2 (ChR2) is activated by blue light?
Na+ and K+ enter, leading to depolarization and action potentials.
Ca2+ exits, causing hyperpolarization.
Cl- enters, resulting in inhibition.
No ions move, and the neuron remains at rest.
Which of the following is NOT an application organism for optogenetics as mentioned in the material?
Worms
Flies
Mice
Frogs
Which organism is known to have the light-activated channel that pumps Cl⁻ into the cell, leading to hyperpolarization and inhibition?
Halobacteria (archaea)
E. coli
Yeast
Cyanobacteria
What is the effect of activating neurons in mice that are not under stress, according to Sterley et al., 2018?
Causes stress-like brain changes and partner mouse is treated as stressed
Prevents brain changes caused by stress
Blocks social transfer of stress
Causes immediate cell death
What is a major challenge in the clinical application of optogenetics for humans?
Requires viral vectors to insert channels, which is not yet safe for humans
Lack of suitable light sources
Inability to target specific neurons
High cost of equipment
During which phases of the action potential does the absolute refractory period occur?
Depolarization and repolarization
Hyperpolarization only
Resting potential only
Depolarization only
Which statement best describes the mechanism of Na⁺ channel gating during the absolute refractory period?
Gate 1 opens at threshold, and Gate 2 (ball-and-chain) closes quickly to inactivate the channel
Both gates remain open throughout the action potential
Gate 2 opens at threshold, and Gate 1 closes slowly
Both gates close simultaneously at the end of repolarization
Based on the research findings, what conclusion can be drawn about the use of optogenetics in neuroscience?
Optogenetics can reveal roles of specific neurons in behavior and disease
Optogenetics is only useful for studying plant cells
Optogenetics cannot be used to study social behavior
Optogenetics is already widely used in human therapy
What is a possible future application of optogenetics mentioned in the document?
Restoring vision by inserting light-sensitive channels in retinal neurons
Treating diabetes by modifying pancreatic cells
Enhancing memory by stimulating hippocampal neurons
Increasing muscle strength by activating motor neurons
Which of the following best describes the "graded potential" in the toilet analogy?
A small lever push resulting in a small water flow.
A full flush resulting in all-or-none response.
The inability to flush while the toilet is flushing.
Flushing during refill, but harder.
What does the "absolute refractory" period in the toilet analogy represent?
A small lever push.
A full flush.
Not being able to flush while the toilet is flushing.
Flushing during refill, but harder.
How do action potentials (APs) travel along the axon?
By diffusion
By propagation
By osmosis
By filtration
Which statement about action potentials (APs) is correct?
APs are graded.
APs decrease in magnitude as they travel.
APs are all-or-none.
APs weaken along the axon.
What is the effect of the refractory period on action potential (AP) frequency?
It allows unlimited AP frequency.
It limits AP frequency to about 1 every 5 ms.
It increases AP frequency to 10 every 5 ms.
It has no effect on AP frequency.
Why does each action potential (AP) not weaken as it travels along the axon?
Because each AP uses new energy locally.
Because the axon is insulated.
Because APs are graded.
Because of potassium influx.
Which feature ensures that information is delivered unchanged to all terminals during nerve impulse transmission?
APs are graded.
APs use new energy locally.
APs are all-or-none.
APs decrease in magnitude.
If a local voltage change of 100 mV occurs, what is its significance in nerve impulse propagation?
It is too small to affect adjacent segments.
It is large enough to bring adjacent segments to threshold.
It causes the axon to hyperpolarize.
It stops the propagation of the AP.
During which phase is another action potential possible but requires a stronger stimulus?
Absolute refractory period
Relative refractory period
Resting potential
Depolarization
What is the main reason for the relative refractory period?
Na+ influx
K+ efflux (channels open and close slowly)
Ca2+ influx
Cl- efflux
What is the maximum firing rate of action potentials (APs) per second?
~200
~20
~2,000
~50
What is the main function of the refractory period in action potential propagation?
To increase the speed of APs
To ensure unidirectional propagation
To decrease the strength of APs
To allow overlapping signals
Which of the following best describes the effect of fast-opening K⁺ channels?
Longer refractory period and lower firing frequency
Shorter refractory period and higher firing frequency
No effect on refractory period
Decreased AP size
How is information about the intensity of a stimulus (such as pain) coded in neurons?
By the size of the action potential
By the timing and frequency of action potentials
By the direction of propagation
By the type of neurotransmitter released
Which analogy is used to explain the directionality of action potentials?
Water flowing in a river
Dominoes falling and needing to be reset
A bouncing ball
A swinging pendulum
What determines which K⁺ channels a neuron has, affecting its refractory period and firing frequency?
Only environmental factors
Only the size of the neuron
Genetics and epigenetic expression
The amount of sodium present
Why do different neurons have different refractory period lengths?
Due to differences in K⁺ channel sensitivity
Because of the size of the action potential
Due to the amount of neurotransmitter released
Because of the direction of AP propagation
A large skin injury results in which of the following, according to the information coding example?
Few APs and mild pain
Many APs and strong pain
No APs and no pain
Slow APs and weak pain
Which cells are responsible for myelination in the peripheral nervous system (PNS)?
Schwann cells
Oligodendroglia
Astrocytes
Microglia
What is the main function of myelin in axons?
Acts as an insulating barrier to prevent ion flow under the sheath
Produces neurotransmitters
Stores calcium ions
Regulates blood flow
What is the speed of action potential conduction in myelinated mammalian axons?
Up to 120 m/s
Up to 30 m/s
Up to 10 m/s
Up to 200 m/s
Which analogy best describes unmyelinated conduction according to the human wave analogy?
Every person in a stadium rises one by one
Only people at the corners rise
Everyone rises at the same time
Only the people in the center rise
What is the primary cause of multiple sclerosis (MS)?
Loss of myelin formed by oligodendroglia in the CNS
Overproduction of neurotransmitters
Excessive neuron growth
Increased blood flow to the brain
Which of the following is a symptom of multiple sclerosis (MS)?
Motor & sensory loss
Increased appetite
Improved vision
Rapid heartbeat
Why is saltatory conduction considered more energy efficient than conduction along unmyelinated axons?
APs are regenerated only at nodes, reducing energy use
It uses more neurotransmitters
It increases the number of ion channels
It requires more ATP
Explain how the pathology of multiple sclerosis (MS) leads to the symptoms observed in patients.
Myelin loss occurs in patches, causing scarring and plaques, which disrupts saltatory conduction and impairs action potential propagation, leading to motor and sensory loss, fatigue, pain, and depression.
Myelin increases neurotransmitter release, causing overstimulation.
Myelin loss increases blood flow, causing headaches.
Myelin loss causes increased neuron growth, leading to tumors.
Which symptom did the 20-year-old patient (C.O.) initially experience in the case study?
Blurred vision leading to optic neuritis
Severe headache
Hearing loss
Abdominal pain
What is the most common disease course for multiple sclerosis (MS) as described in the material?
Relapsing-remitting (RRMS)
Chronic progressive
Acute onset
Latent phase
Which therapy was used for C.O. in the case study, and what is its main purpose?
Interferon beta-1a (Rebif), disease-modifying therapy
Aspirin, pain relief
Insulin, blood sugar control
Penicillin, infection treatment
According to the material, which factor is possibly linked to the higher prevalence of MS in certain latitudes?
Vitamin D deficiency
High sugar intake
Excessive exercise
Air pollution
What is a notable epidemiological feature of MS regarding gender?
It is twice as common in women as in men.
It affects only men.
It is equally common in both genders.
It is more common in children.
Based on the case study, what was one of the side effects experienced by the patient from interferon beta-1a (Rebif) therapy?
Flu-like side effects ("Rebif hangovers")
Severe allergic reaction
Hair loss
Weight gain
Why might MS be more common in northern and southern latitudes, according to the material?
Possibly due to vitamin D deficiency
Due to higher pollution levels
Because of increased physical activity
Due to genetic mutations only found in those regions
What does current research suggest about the nature of MS?
It may be primarily degenerative, with a secondary autoimmune response.
It is caused only by infections.
It is a purely genetic disorder.
It is always curable with medication.
What is the significance of genetic susceptibility in MS, as mentioned in the material?
Family members, such as C.O.'s mother and aunts, may also be affected.
It only affects people with no family history.
Genetics play no role in MS.
It is only passed from father to son.
Which of the following best describes the current treatments for MS?
They modulate immune activity but cannot fully stop the disease.
They cure the disease completely.
They only provide pain relief.
They are all surgical treatments.
Which scientist discovered chemical communication between neurons and won the Nobel Prize in 1936?
Otto Loewi
Ivan Pavlov
Sigmund Freud
Charles Sherrington
What was the main conclusion of Otto Loewi’s experiment with frog hearts?
The vagus nerve releases acetylcholine, which inhibits heartbeat.
The vagus nerve releases epinephrine, which excites heartbeat.
The accelerator nerve releases norepinephrine, which slows heartbeat.
The accelerator nerve releases acetylcholine, which excites heartbeat.
Which chemical messenger is released when the accelerator nerve is stimulated, causing the heart rate to speed up?
Epinephrine (adrenaline)
Acetylcholine
Serotonin
Dopamine
In mammals, which neurotransmitter excites the heart?
Norepinephrine (noradrenaline)
Acetylcholine
Serotonin
GABA
Which of the following best describes the function of acetylcholine (ACh) in the nervous system?
It activates skeletal muscles and can excite or inhibit internal organs depending on the receptor and ion channel.
It only excites skeletal muscles and never affects internal organs.
It always inhibits the heart regardless of the receptor.
It is only found in the brain and not in the peripheral nervous system.
