Nervous System Question
Booklet
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Unit 5- Woodford County High School
Question 1
Unit 5- Woodford County High School
Unit 5- Woodford County High School
Question 2
Unit 5- Woodford County High School
Unit 5- Woodford County High School
Unit 5- Woodford County High School
Question 3
Unit 5- Woodford County High School
Unit 5- Woodford County High School
Question 4
Unit 5- Woodford County High School
Unit 5- Woodford County High School
Question 5
The graph shows the changes in permiability of a neurone membrane to potassium (K+) and
sodium (Na+) ions during the course of an action potential.
Sodium ions
Membrane
permeability
to ions
Potassium ions
Time
(a)
During the course of an action potential, the potential difference across the
neurone membrane changes from –70 to +40 and back to –70 mV. Use the
information in the graph to explain what causes these changes.
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(4)
(b)
(i)
What is meant by the ‘all or nothing’ nature of a nerve impulse?
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(2)
(ii)
Neurones can respond to both strong and weak stimuli. Describe how a
neurone conveys information about the strength of a stimulus.
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(1)
Unit 5- Woodford County High School
(c)
Describe what is meant by temporal summation at a synapse.
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(1)
(Total 8 marks)
Question 6.
The diagram shows some of the pump and channel proteins in the cell surface membrane of a
neurone.
Na+
K+
K+
K+
Na+
Outside
ATP
ADP
K
Structure A
(a)
(i)
Inside
K+ channels
Na+ channel
Na+ gate
What evidence is there in the diagram that structure A is involved in active
transport?
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(1)
(ii)
Explain the role of the Na+ and K+ channels in producing the membrane
resting potential.
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(2)
(b)
Explain how structure A and the Na+ gate allow depolarisation of this membrane.
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(2)
(Total 5 marks)
Unit 5- Woodford County High School
Question 7
(a) Figure 1 shows part of a nerve cell. The numbers show the membrane potential, in
millivolts, at various points along the axon.
–70
–70
–70
+30
–70
–70
–75
–70
–70
–70
Figure 1
(i)
Draw a circle on Figure 1 to show the region of axon membrane most
permeable to potassium ions. Explain your answer.
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(2)
(ii)
Draw an arrow on Figure 1 to indicate the direction in which the nerve
impulse is being conducted. Explain your answer.
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(2)
(b)
The rate of oxygen consumption of a neurone increases when it conducts a high
frequency of impulses. Explain why.
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(4)
Unit 5- Woodford County High School
(c)
Figure 2 shows the positions of two electrodes on the arm of a 20-year-old
volunteer.
Stimulating
electrode
Recording
electrode
Figure 2
The first electrode was used to stimulate motor neurones in the ulnar nerve at different
positions along the arm. Impulses were produced in motor neurones as a result of the
stimulation and travelled along the arm, producing contraction in a muscle near the wrist.
As the muscle started to contract, it produced electrical impulses which were recorded by
the second electrode. The time delay between the stimulation of the nerve and the start of
the muscle contraction was recorded. The results of this investigation have been plotted
on Figure 3.
14
×
12
×
10
×
Time
8
delay / ms
×
6
×
4
×
2
0
0
50
100
150 200 250 300 350 400
Distance between electrodes / mm
450
500
550
600
Figure 3
Draw a line of best fit on Figure 3. Use this line to calculate the speed of an
impulse along the motor neurones in the ulnar nerve of this volunteer. Show your
working.
Answer ..............................................................
(3)
(Total 11 marks)
Unit 5- Woodford County High School
Question 8.
The diagram shows axons from two presynaptic neurones, A and B, and the synapse they
form with postsynaptic neurone, C.
Presynaptic
neurone A
Postsynaptic neurone C
Presynaptic
neurone B
The table shows the results of four experiments to determine the effects of action
potentials in neurones A and B on neurone C.
Experiment
Action potentials in presynaptic neurone(s)
Effect on neurone
C
1
Single action potential in A
No action potential
2
Single action potential in B
No action potential
3
Simultaneous action potentials in A and B
Action potential
4
Two action potentials in A in rapid
succession
Action potential
Explain why an action potential was produced in C in experiments 3 and 4, but not
in experiments 1 and 2.
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(6)
Unit 5- Woodford County High School
Question 9.
The diagram shows dendrites from each of two neurones, A and B, forming synapses
with a third neurone, C. Concentrations of some ions are also shown.
Neurone A
Acetylcholine
Neurone B
0 mV
GABA
–70 m V
Neurone C
Ion concentration/mmol dm–3
Outside neurone C
Inside neurone C
(a)
Na+
145
12
K+
12
155
Cl–
120
5
Acetylcholine increases the permeability of the postsynaptic membrane to Na+
ions. Explain how acetylcholine released from neurone A generates an action
potential in neurone C.
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(3)
(b)
Neurone B releases a substance called GABA as its neurotransmitter. GABA
increases the permeability of the postsynaptic membrane to Cl– ions. Suggest how
impulses in neurone B would reduce the chances of an action potential in neurone
C.
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(2)
(c)
Suggest a benefit of neurone C synapsing with the two types of neurone, A and B.
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(1)(Total 6 marks)
Unit 5- Woodford County High School
Mark Scheme
Question 1
Question 2
Unit 5- Woodford County High School
Question 3
Unit 5- Woodford County High School
Question 4
Question 5
(a)
(b)
Initially membrane impermeable to Na+;
Sodium channels open;
allowing Na+ into axon;
reverses potential difference across membrane/ charge on either
side/depolarised;
membrane becomes more permeable to K+ ions/K+ leave the axon;
(i)
(ii)
(c)
max. 4
All action potentials are the same size;
threshold value for action potential to occur
2
frequency of action potentials
1
several (sub-threshold) impulses add to produce an action potential
1
[8]
Unit 5- Woodford County High School
Question 6.
(Sodium/Na+ - potassium/K+ throughout)
(a)
(b)
(i)
ATP converted/used/energy from ATP;
1
(ii)
More potassium pores than sodium pores/more permeable to K+/
less permeable to Na+;
more potassium / + ve ions (leaks) out;
R.ref to active transport
R. refs to channel opening/closing
therefore more positive on outside/ORA;
max. 2
Sodium ions pumped out (to create diffusion gradient);
sodium gates open/via Na+ gate to allow sodium ions (to flood) in;
I refs to K+
2
[5]
Question 7. (a)
OR
(ii)
(b)
(c)
(i)
Circle drawn to include ‘+30’ region of neurone;
Reference to depolarised membrane/ change in membrane opening
potassium
channels
Idea that ‘this is voltage to start repolarisation’;
2
Arrow pointing to left hand margin of paper plus written idea that
impulse has passed the -75mV point; = 1 mark
Arrow pointing to left hand margin of paper plus reference to
hyperpolarisation/ description in terms of ion flow;; = 2 marks
[Accept: Description of repolarisation including ‘overshoot I
[Reject: Both marks if arrow incorrect]
Oxygen used in respiration; [Reject: Anaerobic reference]
Valid reference to ATP/energy; [Reject: Production of energy]
(For) sodium-potassium pump/ active transport of ions/ uptake/ synthesis
of transmitter/ vesicle movement;
(Higher rate of impulses means) more high / amount of sodium ion entry/
potassium ion loss / transmitter uptake / release / vesicle movement;
(i)
Accurate line of best fit;
Correct working shown, i.e. distance as a number using candidates line;
Time as a number
Correct answer in ms/m/s using candidates line;
[Note: Allow 2 marks for correct answer in mm/ms or equivalent even if
no best fit line or working shown]
2
4
3
[11]
Unit 5- Woodford County High School
Question 8.
postsynaptic neurone has ‘high’ threshold;
simultaneous arrival of impulses from two presynaptic neurones produces
sufficient transmitter substance;
to cause depolarisation / action potential in postsynaptic neurone /
reach threshold (once only);
this is spatial summation;
impulses in rapid succession from one presynaptic neurone produce sufficient transmitter
substance;
to cause depolarisation / action potential in postsynaptic neurone /
reach threshold (once only);
this is temporal summation;
insufficient transmitter substance produced in A / B;
to cause depolarisation / action potential in postsynaptic neurone /
reach threshold (once only);
max 6
Question 9.
(a)
ACh combines with receptor (on neurone C / on postsynaptic membrane);
causes influx of Na+ ions;
down gradient / diffuse;
less negative/more positive inside/ ‘depolarisation’ occurs;
reference to above threshold (to generate action potential);
(b)
(c)
max 3
(Cl– entry to neurone C) makes potential more negative inside/hyperpolarises;
requires more stimulation (from A) / ACh / Na+/ more impulses;
2
Reference to modulation of activity of neurone C / impulse transmission not
inevitable / eq;
1
[6]
Unit 5- Woodford County High School