Author: Philip Colls
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Nerves booklet revision questions                  NAME:
Q1.
(a)     The following statements are about events during an action potential.
A Potassium ions diffuse out across the neurone membrane.
B Sodium ions diffuse in across the neurone membrane.
C Sodium ion channels open.
D Active transport of sodium and potassium ions restores resting potential.
E Potassium ion channels open.
F Hyperpolarisation of the membrane occurs.
(i)      Which of the events, A to F, starts depolarisation?
Put the correct letter in the box.
 
(1)
(ii)      Which of the events, A to F, requires the hydrolysis of ATP?
Put the correct letter in the box.
 
(1)
(b)     Synaptophysin is a protein involved in the production of synaptic vesicles.
Scientists can use the presence or absence of synaptophysin to identify presynaptic and postsynaptic membranes in synapses.
Explain why they are able to use synaptophysin for this purpose.
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(1)
(c)     Dopamine is a neurotransmitter. Production of too much dopamine is associated with schizophrenia. A drug used to treat schizophrenia binds to dopamine receptors in synapses. This binding does not lead to the formation of an action potential.
(i)      Suggest why the drug used to treat schizophrenia is able to bind to the same receptor as dopamine.
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(1)

(ii)      Suggest why binding of the drug does not lead to production of an action potential.
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(2)
(Total 6 marks)
Q2. The resting potential of a neurone is maintained by the unequal distribution of ions inside and outside the plasma membrane. The diagram shows the plasma membrane of a neurone and the three different proteins that are involved in maintaining the resting potential.
 
(a)     Protein C requires ATP to function. Describe the role of protein C.
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(2)
(b)     (i)      Proteins A and B differ from each other. Explain why different proteins are required for the diffusion of different ions through the membrane.
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(2)
(ii)     The plasma membrane of the neurone is more permeable to potassium ions than to sodium ions. Give the evidence from the diagram that supports this observation.
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____________________________________________(1)  (Total 5 marks)
Q3.
(a)     A myelinated axon conducts impulses faster than a non-myelinated axon.
Explain this difference.
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(3)
Doctors investigated the relationship between myelin in brain tissue and different types of dementia. All types of dementia involve loss of mental ability.
The doctors measured the mean amount of myelin in samples of brain tissue from:
•        a control group of 12 people without dementia
•        20 people with vascular dementia (VaD)
•        19 people with Alzheimer's dementia (AD)
•        31 people with Lewy body dementia (LD).
The doctors’ results are shown in the figure. The vertical bars show standard errors.
 
Group of people

(b)     The doctors used a statistical test to compare the results for AD and LD.
They obtained a value for P of 0.047. What does this result show about the difference between the means for AD and LD?
Use the words probability and chance in your answer.
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(c)     A student who read this investigation concluded that there was a relationship between the amount of myelin in a person’s brain and whether or not they had dementia. Do these data support this conclusion? Give reasons for your answer.
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____________________________________________________ (4) (Total 9 marks)
Q4. The body loses heat quickly in cold water. A researcher investigated the effect of length of time in a bath of ice-cold water on the reaction times of 20 healthy people aged between 21 and 23 years of age.
She measured each person’s reaction time after being left in ice-cold water for 15, 30 or 45 seconds. She also recorded each person’s reaction time before being placed in the ice-cold water (0 seconds).
The table shows her results.

Length of time in bath of
ice-cold water / seconds

Mean reaction time / seconds

Standard error

0 | 0.395 | 0.0124
15 | 0.301 | 0.0105
30 | 0.297 | 0.0212
45 | 0.326 | 0.0183
(a)     (i)      One reason that reaction time is slower when body temperature falls is because nerve impulse conduction is slower. Explain how a lower temperature leads to slower nerve impulse conduction.
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(2)
(ii)     Other than temperature, give two factors that affect the speed of nerve impulse conduction.
1. ____________________________________________________________
2. __________________________________________________________(2)
(b)     Suggest the conditions that the researcher used when obtaining her data for 0 seconds.
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(c)     Explain how the researcher could use her raw data to find
(i)      the mode_______________________________________________________
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(ii)     the range_______________________________________________________
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(d)     A student reading the researcher’s report concluded that the difference between the results for 30 seconds and 45 seconds was significant. Do you agree with his conclusion? Explain your answer.
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 (3)
(Total 10 marks)
Q5. (a)     Figure 1 shows the changes in membrane potential at one point on an axon when an action potential is generated.
Figure 1
 
The changes shown in Figure 1 are due to the movement of ions across the axon membrane. Complete the table by giving the letter (A to D) that shows where each process is occurring most rapidly.
 
Process | Letter
Active transport of sodium and potassium ions |
Diffusion of sodium ions |
Diffusion of potassium ions |
(2)
(b)     Figure 2 shows the relationship between axon diameter, myelination and the rate of conduction of the nerve impulse in a cat (a mammal) and a lizard (a reptile).
Figure 2
 
(i)      Explain the effect of myelination on the rate of nerve impulse conduction.
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____________________________________________________________(2)
S       (ii)     For the same diameter of axon, the graph shows that the rate of conduction of the nerve impulse in myelinated neurones in the cat is faster than that in the lizard. Suggest an explanation for this.
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Figure 3 shows how a stimulating electrode was used to change the potential difference across an axon membrane. Two other electrodes, P and Q, were used to record any potential difference produced after stimulation. The experiment was repeated six times, using a different stimulus potential each time. In experiments 1 to 4, the stimulating voltage made the inside of the axon less negative. In experiments 5 and 6, it made the inside of the axon more negative.
Figure 3

(c)     Explain the results of experiments 1 to 4.
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(d)     Figure 4 shows two neurones, X and Y, which each have a synapse with neurone Z.
Figure 4
 
Neurone X releases acetylcholine from its presynaptic vesicles. Neurone Y releases a different neurotransmitter substance which allows chloride ions (Cl^‑) to enter neurone Z. Use this information, and information from Figure 3, to explain how neurones X and Y have an antagonistic effect on neurone Z.
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___________________________________________________ (4) (Total 15 marks)
Q6. During an action potential, the permeability of the cell-surface membrane of an axon changes. The graph shows changes in permeability of the membrane to sodium ions (Na^+) and to potassium ions (K^+) during a single action potential.
 
(a)     Explain the shape of the curve for sodium ions between 0.5 ms and 0.7ms.
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(b)     During an action potential, the membrane potential rises to +40 mV and then falls. Use information from the graph to explain the fall in membrane potential.
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(c)     After exercise, some ATP is used to re-establish the resting potential in axons. Explain how the resting potential is re-established.
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____________________________________________________(2)(Total 8 marks)
Q7.
(a)    Describe how a heartbeat is initiated and coordinated.

(5)
(b)     Explain how the heart muscle and the heart valves maintain a one-way flow of blood from the left atrium to the aorta.

(5)
(Total 10 marks)
Q8. Figure 1 shows changes in the membrane potential of a neurone during one action potential.
Figure 1
 
(a)     What happens in the membrane to cause the change in membrane potential at time B?
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(b)     No further action potential can be produced between times A and C. What is the name given to the period between times A and C?
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(c)     Figure 2 shows the force generated by a muscle when it was stimulated by different frequencies of nerve impulse.
Figure 2
 
A taser is a device used by the police to arrest violent suspects. It fires electrical impulses very similar to action potentials into a suspect. The frequency of the impulses is between 15 and 20 per second.
(i)      Suggest the effect a taser has on a suspect’s muscles.
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(ii)     Tasers with frequencies of between 40 and 80 per second are not used, because they are considered too dangerous. Suggest how they might be dangerous to a suspect.
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_______________________________________________(2)  (Total 7 marks)
Q9. (a)     Exercise causes an increase in heart rate. Describe the role of receptors and of the nervous system in this process.
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(b)     AMP-activated protein kinase (AMPK) is an enzyme that regulates a number of cellular processes. Exercise leads to activation of AMPK. The diagram shows one effect of activation of AMPK during exercise.
 
CPT1 is a channel protein that transports fatty acids into mitochondria. Using the diagram above, explain the benefit of activation of AMPK during exercise.
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_____________________________________________________(3)(Total 7 marks)
Q10. Cocaine is a highly addictive and illegal drug. The release of the neurotransmitter dopamine in specific synapses in the brain leads to feelings of pleasure. Dopamine is removed from synapses by dopamine transporter proteins in the plasma membrane of neurones. Cocaine binds to the dopamine transporter protein.
Figure 1 shows a dopamine transporter protein and molecules of cocaine and dopamine.
Figure 1
 
(a)     Using all of the information, suggest how cocaine leads to feelings of pleasure.
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 (3)
(b)     (i)      Scientists isolated a mutated gene for the dopamine transporter protein.
Name one method that the scientists could have used to produce many copies of the mutated gene in the laboratory.
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(ii)     Copies of the gene were then inserted into early embryos of mice. When these mice were born, samples of their DNA were tested using DNA probes to make sure that the mutated gene was present in the mice.
What is a DNA probe?
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(c)     Figure 2 shows dopamine transporter proteins produced from the normal gene and from the mutated gene.
Figure 2
 
Explain how the mutation leads to the production of a protein that transports dopamine but is not affected by cocaine.
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_________________________________________________ (3)  (Total 9 marks)
Q11.
Body position | Pulse rate / beats per minute
| Reading 1 | Reading 2 | Reading 3 | Mean
Sitting | 80 | 76 | 76 | 77
Standing | 84 | 88 | 92 | 88
Lying down | 68 | 72 | 68 | 69
(a)     Using the results in the table above, calculate the percentage decrease in mean pulse rate when lying down compared with when standing.
Answer = ______________________________________ %    (2)
(b)     When the heart beats, both ventricles contract at the same time.
Explain how this is coordinated in the heart after initiation of the heartbeat by the SAN.
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__________________________________________________(2)  (Total 4 marks)
Q12. Acetylcholine is a neurotransmitter which binds to postsynaptic membranes and stimulates the production of nerve impulses. GABA is another neurotransmitter. It is produced by certain neurones in the brain and spinal cord. GABA binds to postsynaptic membranes and inhibits the production of nerve impulses. The diagram shows a synapse involving three neurones.
 
(a)     Describe the sequence of events leading to the release of acetylcholine and its binding to the postsynaptic membrane.
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(4)
(b)     The binding of GABA to receptors on postsynaptic membranes causes negatively charged chloride ions to enter postsynaptic neurones. Explain how this will inhibit transmission of nerve impulses by postsynaptic neurones.
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(3)
(c)     Epilepsy may result when there is increased neuronal activity in the brain.
(i)      One form of epilepsy is due to insufficient GABA. GABA is broken down on the postsynaptic membrane by the enzyme GABA transaminase. Vigabatrin is a new drug being used to treat this form of epilepsy. The drug has a similar molecular structure to GABA. Suggest how Vigabatrin may be effective in treating this form of epilepsy.
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(2)

(ii)     A different form of epilepsy has been linked to an abnormality in GABA receptors. Suggest and explain how an abnormality in GABA receptors may result in epilepsy.
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(3)
(d)     During an epileptic seizure muscular contractions may occur. In which part of the brain would neuronal activity produce muscular contractions of the right leg?
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(2)
(Total 14 marks)

Mark schemes
Q1.
(a)     (i)      C;
1
(ii)     D;
1
(b)     (Synaptic) vesicles (only) found in presynaptic (part of synapse);
Accept bulb of synapse for presynaptic
Reject vesicles in the membrane
1
(c)      (i)      Has similar shape/structure to dopamine
OR
Complementary (to binding site on receptor);
Ignore competitive inhibitor
Accept tertiary structure
Reject active site
Reject same shape as dopamine/as receptor
1
(ii)     1.      (Binding) does not lead to opening of sodium ion channels;
2.      (So) no depolarisation / threshold not reached / sodium ions do not diffuse in;
OR
3.      Opens chloride ion channels;
4.      Causing hyperpolarisation / preventing depolarisation
Mark either 1 and 2 OR 3 and 4
1. Accept stops dopamine opening sodium ion channels
1. Reject sodium unqualified
2. Accept no generator potential
3. Reject chlorine
2
[6]
Q2.
(a)     Transports Na^+ and K^+ ;
By active transport / pump / against concentration gradient;
Restores ion balance after an action potential;
[reject K^+ out and Na^+ in]
2
(b)     (i)     each protein has a specific tertiary structure / shape;
because the ions have different sizes / shape / charge;
[reject receptors binding]
2
(ii)     fewer protein B molecules, which transport sodium ions / more 
protein A molecules, which transport potassium ions;
1
[5]
Q3.
(a)     1.      (In myelinated) action potential / depolarisation only at node(s);
2.      (In myelinated, nerve impulse) jumps from node to node / saltatory;
3.      (In myelinated) action potential / impulse does not travel along whole length;
The question is about speed of transmission, not repolarisation or related matters
Accept converse for non-myelinated
3
(b)     1.      Probability of obtaining this difference by chance;
Reject ‘results’ once only
This statement often split round 2.
2.      Is less than 5% / less than 0.05 / less than one in twenty;
Accept is 4.7% / 0.047 but reject less than 4.7% / 0.047
Accept correct greater than 95% / greater than 0.95 arguments
3.      Difference is significant;
Reject ‘results’ once only
2 max
(c)     1.      (All) dementia results lower (than control group) / non-dementia result higher;
2.      Error bars do not overlap so differences are (possibly) significant;
Neutral results
Accept not due to chance / statistically significant
In this context, accept references to standard deviation
3.      Dementia may be due to other factors / not only due to a lack of myelin;
Accept suitable named factor e.g. genetic
4.      (Because) big / significant differences in myelin in different dementia;
Not just ‘different’
5.      Only small sample sizes / only one study / more data required;
4 max
[9]
Q4.
(a)     (i)      1.      Slower diffusion;
Accept description of diffusion eg ‘movement down concentration gradient’ but concept of slower is required
2.      (Of) ions / Na^+ / K^+;
Reference to ions is required. Reject other named ions, eg calcium ions
Ignore references to synaptic transmission or rates of respiration
2
(ii)     1.      Myelination / saltatory conduction;
Accept reference to presence of nodes of Ranvier
2.      Axon diameter;
2
(b)     Keep everything the same but not in bath / at room temperature / same clothing as for immersion / sitting in empty bath / sitting in water at room temperature;
Accept ‘normal’ or ‘comfortable’ as equivalent to room temperature
Ignore reference to body temperature
1
(c)     (i)      (Find) the most common result / time / the result / time that occurs the most;
1
(ii)     Highest and lowest result / time;
Accept ‘difference between highest and lowest results / times’
1
(d)     1.      (Which is based on) mean of 20 people / large (enough) sample;
This point is possible for students that suggest the difference is significant
2.      (But) SE bars / confidence limits overlap;
This point applies whether 1 × SE or 2 × SE is used
3.      Reference to 0.297 ± 0.0424 / 0.326 ± 0.0366 / confidence limits = 2 × SE;
This point rewards knowledge of use of 2 × SE (as per Students’ Statistics Sheet)
4.      (So) difference is not significant;
This point is only awarded after marking point 2 or marking point 3 has been given
3 max
[10]
Q5.
(a)     In table:
 
D | All 3 correct = 2 marks;;
B | 2 correct = 1 mark;
C | 0 or 1 correct = 0 marks
2
(b)     (i)      myelin insulates / prevents ion movement; saltation / described 
re leaping node to node;
2
(ii)     cat has higher body temperature;
ignore references to homoiothermy’ / warm-blooded
faster diffusion of ions / faster opening of ion pores / gates / channels;
2
(c)     1       increasing stimulus (potential) causes decrease in potential
difference / rise in potential at P;
2       1 or 2 is sub-threshold / 1 or 2 does not give action potential / 3 or 4 is above threshold / 3 or 4 does give an action potential;
3       influx of Na^+ ions; (not just Na / sodium)
4       voltage-gated channels (in axon membrane) opens / opens Na^+
channels / membrane more permeable to Na^+
(NOT just Na / sodium);
5       sufficient for stimulation of adjacent region of axon therefore impulse propagated (from P to Q);
5
(d)     1       X / Acetylcholine → opening of Na^+ channels / increases
Na^+ permeability and Na^+ ion entry into Z;
2       Y / Cl^– entry - lowers potential / increases potential
difference / makes potential more negative;
3       X stimulates and Y inhibits (Z);
4       balance of impulses from X and Y determines whether Z
fires action potential / determines whether potential rises
above threshold;
4
[15]
Q6.
(a)     (Ion) channel proteins open, sodium in;
Changes membrane potential / makes inside of axon less
negative / positive / depolarisation / reaches threshold;
More channels open / positive feedback;
Accept other phrases for ion channel proteins providing that it is clear that it is something through which ions pass.
Reject carrier.
First marking point relates to opening.
Third point must relate to more (channels) opening.
3
(b)     Potassium channels open;
Potassium out;
Sodium channels close;
Do not penalise candidate who refers to sodium or potassium. Ions are mentioned in question.
Reject pump
3
(c)     Pump / active transport / transport against concentration gradient;
Of sodium from axon / sodium out / of potassium in;
Do not penalise candidate who refers to sodium or potassium. Ions are mentioned in question
2
[8]
Q7.
(a)     1.      SAN sends wave of electrical activity / impulses (across atria) causing atrial contraction;
Accept excitation
2.      Non-conducting tissue prevents immediate contraction of ventricles / prevents impulses reaching the ventricles;
3.      AVN delays (impulse) whilst blood leaves atria / ventricles fill;
4.      (AVN) sends wave of electrical activity / impulses down Bundle of His;
4. Allow Purkyne fibres / tissue
5.      Causing ventricles to contract from base up;
5
(b)     1.      Atrium has higher pressure than ventricle (due to filling / contraction) causing atrioventricular valves to open;
Start anywhere in sequence, but events must be in the correct order.
1. Accept bicuspid, reject tricuspid
1. Allow: blood passes through the valve = valve open / blood stopped from passing through the valve = valve closed
2.      Ventricle has higher pressure than atrium (due to filling / contraction) causing atrioventricular valves to close;
3.      Ventricle has higher pressure than aorta causing semilunar valve to open;
Points 1, 2 and 3 must be comparative: eg higher 3. Allow aortic valve
4.      Higher pressure in aorta than ventricle (as heart relaxes) causing semilunar valve to close;
4. Allow aortic valve
5.      (Muscle / atrial / ventricular) contraction causes increase in pressure;
5
[10]
Q8.
(a)     Potassium channels open (and K^+ ions diffuse out);
Accept references to sodium channels opening;
Sodium channels close (and stops Na^+ ions diffusion in);
Leading to depolarisation;
Accept sodium pump (starts) to pump out sodium ions
2
(b)     (Absolute) refractory (period);
1
(c)     (i)      Causes them to contract;
And relax;
Rapidly/twitch;
2 max
(ii)     Cause continuous muscle contraction;
Accept a reasonable suggestion of harm ‒ linked
to muscle contraction
At high force;
Causing failure to breathe/heart stops pumping/
damage to bones or joints;
2 max
[7]
Q9.
(a)     1.      Chemoreceptors detect rise in CO_2 / H_+ / acidity / carbonic acid / fall in pH
OR
Baro / pressure receptors detect rise in blood pressure;
2.      Send impulses to cardiac centre / medulla;
3.      More impulses to SAN;
4.      By sympathetic (nervous system for chemoreceptors / CO_2)
OR
By parasympathetic (nervous system for baro / pressure receptors / blood pressure);
1.      Ignore: location of receptors.
1.      Ignore: chemoreceptors detect oxygen.
2 and 3. Accept: action potentials.
2.      Reject: ‘messages’, ‘signals’, ‘an impulse’ or an ‘action potential’.
3.      Ignore: messages’, ‘signals’, ‘an impulse’ or an ‘action potential’ as emphasis here is on increase in frequency.
4
(b)     1.      Less / no malonyl-CoA;
2.      (More) fatty acids transported / moved into mitochondria;
3.      Respiration / oxidation of fatty acids provides ATP;
1.      ‘Inhibition of malonyl-CoA’ on its own is not enough but accept production of malonyl-CoA is inhibited.
2.      Accept: ‘transport of fatty acids into mitochondria is not inhibited’.
2.      Ignore: method of entry.
3.      Accept: for respiration any stage of aerobic respiration e.g. Krebs (cycle), link (reaction) etc.
3.      Reject: production of energy, but accept production of energy in the form of ATP.
3.      Accept: acetyl CoA can enter Krebs cycle / mitochondria to provide ATP.
3
[7]
Q10.
(a)     Cocaine (binding) changes shape of transporter/prevents dopamine binding;
Reject references to active site
Transporter cannot move (bound) dopamine (through membrane / protein /
into cell);
Dopamine remains / builds up in synapses (leading to feelings of pleasure);
3
(b)     (i)      Polymerase chain reaction / PCR;
1
(ii)     Single-stranded DNA;
Reject reference to a single strand of DNA
Bases / sequence complementary to DNA / gene to be identified;
(Radioactively / fluorescent) labelled so that it can be detected;
2 max
(c)     Mutation changes base sequence of gene / DNA;
Accept references to active site
(Thus) changing amino acid sequence;
Changes tertiary structure / shape of protein/transporter;
Cocaine binding site changes/cocaine cannot bind;
Dopamine can still bind (and be transported);
3 max
[9]
Q11.
(a)     21.59 / 21.6;
19/88 × 100 = 1 mark
Accept for 1 mark - 19/69 × 100 = 27.5%;
(only award if rounding correct)
Max 1 for incorrect rounding
Accept any number of significant figures
as long as the rounding is correct
2
(b)     1.      Electrical activity only through Bundle of His / AVN;
2.      Wave of electrical activity passes over / through both ventricles at the same time;
For ‘electrical activity’ accept impulses / depolarisation / action potential
Reject messages/signals/information once only
2. Accept ‘wave of electrical activity passes through the Purkinje / Purkyne fibres / tissue’
2
[4]
Q12.
(a)     action potential arrives / depolarisation occurs;
calcium ions enter synaptic knob;
vesicles fuse with membrane;
acetylcholine diffuses (across synaptic cleft);
binds to receptors;
4 max
(b)     inside becomes more negatively charged / hyperpolarised; stimulation does not reach threshold level / action potential not produced;
depolarisation does not occur / reduces effect of sodium ions entering;
3
(c)    (i)       inhibits enzyme (which breaks down GABA);
more GABA available (to inhibit neurone);
OR
binds to (GABA) receptors;
inhibits neuronal activity / chloride ions enter (neurone);
2 max
(ii)     receptors have different tertiary / 3D structure / shape not complementary;
GABA cannot bind; inhibition of neuronal activity does not occur / chloride ions do not enter;
3
(d)     motor area;
left cerebral hemisphere;
2
[14]