1 markWhich of the following rows, A to D, shows a correct difference between myelinated and unmyelinated neurones?
| Â | Myelinated neurone | Unmyelinated neurones |
| A | Impulse transmission is slower | Impulse transmission is faster |
| B | Action potential occurs at the nodes of Ranvier | Action potential can happen anywhere along the membrane of the axon |
| C | Consists of an axon | Consists of Schwann cells |
| D | Saltatory conduction cannot occur | Saltatory conduction can occur |
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1 markWhich statement describes an aspect of resting potential?
The axon is permeable to sodium ions
The inside of the axon is negatively charged compared to the outside
Potassium ions are pumped out of the axon by active transport
3 potassium ions are pumped into the axon by active transport
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1 markWhich of the statements about the Pacinian corpuscle is/are correct?
| 1 | Pacinian corpuscles are transducers that converts mechanical pressure into electrical impulses |
| 2 | The lamellae layers contain stretch-mediated sodium ion channels |
| 3 | A generator potential is produced when sodium ions leave the axon |
1, 2 and 3
Only 1 and 2
Only 2 and 3
Only 1
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1 markThe image below shows changes in membrane potential during an action potential.
Which of the following describes the process taking place at P?
Voltage-gated sodium ion channels in the axon membrane open
Voltage-gated potassium ion channels in the axon membrane open
Diffusion of potassium ions out of the axon
Diffusion of sodium ions out of the axon
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1 markThe figure below shows a drawing of a synapse.
Which of the rows, A to D, correctly identifies the name of the structure labelled X and the functions of the structures labelled Y and Z?
| Â | Name of structure X | Function of structure Y | Function of structure Z |
| A | Synaptic cleft | Allows an influx of calcium ions | Binds to neurotransmitter |
| B | Synaptic cleft | Allows an influx of sodium ions | Binds to calcium ions |
| C | Synaptic knob | Allows an influx of calcium ions | Binds to neurotransmitter |
| D | Synaptic knob | Allows an influx of sodium ions | Binds to calcium ions |
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1 markRefer to the diagram below of a synapse.
Which of the following statements, A to D, describes events occurring at a synapse?
Acetylcholine is broken down by enzymes so that it can bind to structure K.
An action potential causes structure J to close.
Structure J is a voltage gated Ca2+ channel.
Structure L is released by exocytosis.
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1 markRefer to the diagram below of a synapse.
GABA is a neurotransmitter.
GABA reduces the number of action potentials in the postsynaptic neurone by opening chloride ion channels in the post-synaptic membrane.
Which of the following statements, A to D, describes the action of GABA?
GABA binds to structure K in competition with acetylcholine.
GABA causes hyperpolarisation of the post-synaptic membrane.
GABA causes depolarisation of the post-synaptic membrane.
GABA inhibits release of neurotransmitter from structure L.
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1 markThe image below shows a synaptic bulb.
Which of the following rows, A to D, correctly names the parts labelled H to J in the image?
| Â | H | I | J | K |
| A | vesicle containing neurotransmitter |
mitochondrion | dendron | postsynaptic membrane |
| B | vesicle containing Ca2+ | mitochondrion | axon | presynaptic membrane |
| C | vesicle containing Ca2+ | myelin | dendron | postsynaptic membrane |
| D | vesicle containing neurotransmitter |
mitochondrion | axon | presynaptic membrane |
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1 markThe table below shows the membrane potentials of different neurones at a cholinergic synapse.
The data were recorded on five separate occasions, as shown in the five rows.
| Â | Membrane potential (mV) |
|||
| Â | Presynaptic neurone A |
Presynaptic neurone B |
Presynaptic neurone C |
Postsynaptic neurone |
| 1 | +40 | –70 | –70 | –70 |
| 2 | –70 | +40 | –70 | –70 |
| 3 | –70 | –70 | +40 | –70 |
| 4 | +40 | +40 | –70 | –70 |
| 5 | +40 | +40 | +40 | +40 |
Which of the following, A to D, explains these data?
divergence
hyperpolarisation
spatial summation
temporal summation
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1 markThe drug metoprolol prevents stimulation of post-synaptic receptors in the sympathetic nervous system.
Which of the following conditions could this drug be used to treat?
1, 2 and 3
Only 1 and 2
Only 2 and 3
Only 1
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1 markAnimals receive different stimuli from their environment. Their synapses can manage multiple stimuli, often resulting in one response (such as a muscle twitching).
This action of the synapse is an example of
spatial summation
all or nothing response
temporal summation
cell signalling
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1 markWhich of the following describes the process that happens during repolarisation of a neurone during the action potential?
Â
| Â | Sodium channels | Potassium channels | Membrane potential |
| A | closed | open | decreasing |
| B | open | closed | decreasing |
| C | open | closed | increasing |
| D | closed | open | increasing |
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1 markThe diagram below shows the left to right transmission of an action potential in a myelinated axon by saltatory conduction.
Which of the following rows correctly identifies I - IV?
| Â | I | II | III | IV |
| A | Node at resting potential | Node at action potential | Node at refractory period | Node becoming depolarised |
| B | Node at refractory period | Node at action potential | Node becoming depolarised | Node at resting potential |
| C | Node at action potential | Node at refractory period | Node becoming depolarised | Node at resting potential |
| D | Node at refractory period | Node becoming depolarised | Node at action potential | Node at resting potential |
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1 markThe diagram below shows a sodium-potassium pump within the axon membrane of a neurone.
Which statement correctly describes the role of the sodium-potassium pump in transmission of nerve impulses by neurones?
The sodium-potassium pump establishes the resting potential needed for impulse transmission by actively pumping three sodium ions out of the axon for every two potassium ions it pumps into the axon.
The sodium-potassium pump initiates depolarisation by actively pumping sodium ions into the axon.
The sodium-potassium pump establishes the resting potential needed for impulse transmission by actively pumping two sodium ions into the axon for every three potassium ions it pumps out of the axon.
The sodium-potassium pump initiates the action potential needed for the transmission of an impulse by pumping potassium ions into the axon once the threshold membrane potential is reached.
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1 markThe oscilloscope trace shown below was taken using a digital oscilloscope. It shows an action potential, in a neurone of a potoroo (a small marsupial species), that occurred when the neurone was stimulated with a current pulse.
How many action potentials could be stimulated in this neurone every second?
6
60
12
7
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1 markWhich of the following statements about a Pacinian corpuscle is not correct?
The receptors are found in the skin and consist of lamellae layered up at the terminal end of the axon of a sensory neurone.
Greater pressure results in the opening of more stretch-mediated sodium ion channels and therefore there is a bigger intake of sodium ions and stimulation of more action potentials.
Stretching of lamellae in the Pacinian corpuscle results in intake of sodium ions through stretch mediated sodium ion channels to produce multiple generator potentials.
Differential pressure produces the same response if the threshold value is reached.
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1 markWhich of the following diagrams, A to D, shows a sensory neurone?
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1 markThe image below is a diagram of a Pacinian corpuscle, found deep within the skin.
Which of the following, A to D, explains the generation of an action potential in the Pacinian corpuscle?
Influx of potassium ions into the neurone down their electrochemical gradient
Voltage-gated sodium ion channels open to allow diffusion of sodium ions
Repolarisation of the axon membrane results in a generator potential
The neurone ending has stretch-mediated channels that can change shape
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1 markThe table below shows the action potential propagation velocity for two different neurons with varying axon diameter.
Axon diameter (μm) |
Action potential propagation velocity (m/s) | |
| Neurone A | Neurone B | |
| 0.2 | 1.0 | 1.0 |
| 0.4 | 1.8 | 1.4 |
| 0.6 | 3.0 | 1.8 |
| 0.8 | 3.8 | 2.2 |
| 1.0 | 4.0 | 2.6 |
Which of the following, A to D, is the most likely explanation for this data?
Resistance decreases as axon diameter increases
Neurone A has a longer refractory period than neurone B
Spatial summation occurs when both neurone A and neurone B are connected to the postsynaptic neurone
Saltatory conduction happens along neurone A and continuous conduction happens along neurone B
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1 markWhich row in the table correctly describes how resting potential is established and maintained?
| Â | Movement of ions | Channels |
| A | 2 sodium ions pumped out of axon | All voltage gated channels closed, potassium channels open, sodium channels closed |
| B | 3 sodium ions pumped out of axon | All voltage gated channels closed, potassium channels open, sodium channels closed |
| C | 3 sodium ions pumped out of axon | Voltage gated potassium channels open, voltage gated sodium channels closed, potassium channels open, sodium channels closed |
| D | 2 sodium ions pumped out of axon | Voltage gated potassium channels open, voltage gated sodium channels closed, potassium channels open, sodium channels closed |
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1 markAcetylcholine is a neurotransmitter involved in brain functions such as enhanced attention. Nicotine is a drug found in cigarettes that has the same shape as acetylcholine and that works by enhancing the effect of acetylcholine release.Â
Which statement(s) correctly explain(s) why nicotine can enhance attention in the brain?
| 1 | Nicotine binds with the cholinergic receptors in the postsynaptic membrane. |
| 2 | Sodium ion channels open to allow an influx of sodium ions into the neurone. |
| 3 | Nicotine blocks the ACh receptors and prevents the generation of a new action potential in the postsynaptic neurone. |
1, 2 and 3
Only 1 and 2
Only 2 and 3
Only 1
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1 markThe graph represents a summation process in a postsynaptic neurone at a cholinergic synapse.
Which of the statements about the graph is correct?
A larger action potential is generated from multiple impulses
Acetylcholine builds up to a high enough level in the synaptic cleft, allowing a threshold to be reached and triggering an action potential
Hyperpolarisation is occurring above the threshold
Impulses from multiple synaptic knobs arriving at the same time are added together to reach the threshold
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