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A2 Biology Exam DoctorNERVOUS COORDINATION
Question
2
Question
3
Question
1
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A2 Biology Exam DoctorNERVOUS COORDINATION
QUESTION 1
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The diagram below shows a recording of an action potential passing along a
nerve axon.
(a) (i) What is meant by the term threshold stimulus?
[1]
(ii) By means of an arrow, indicate on the diagram the probable time when the
stimulus was applied. [1](iii) What is the state of the axon membrane from A to B?
[1]
(b) (i) Describe the changes that are occurring in the axon during the period B to D.
[2]
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The diagram below shows a recording of an action potential passing along a
nerve axon.
(a) (i) What is meant by the term threshold stimulus?
[1]
(ii) By means of an arrow, indicate on the diagram the probable time when the
stimulus was applied. [1](iii) What is the state of the axon membrane from A to B?
[1]
(b) (i) Describe the changes that are occurring in the axon during the period B to D.
[2]
e in
tensity of stimulus needed to get a nerve impulse generat
Resting.
brane becomes permeable to sodium ions and they rush in.
inside becomes positively charged.
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The diagram below shows a recording of an action potential passing along a
nerve axon.
(a) (i) What is meant by the term threshold stimulus? [1]
(ii) By means of an arrow, indicate on the diagram the probable time when thestimulus was applied. [1]
(iii) What is the state of the axon membrane from A to B? [1]
(b) (i) Describe the changes that are occurring in the axon during the period B to D.
[2]
(a)(i) the smallest stimulus that is capable of setting up an action potential; 1
(ii) put arrow on or near to 0.7 millisecond; 1
(iii) at the resting potential; 1
(b)(i) stimulus makes axon membrane become permeable to sodium ions;
these flood into the axon along the diffusion gradient;
thus polarity of membrane reverses to give action potential; max 2
TOTAL 5
MARK SCHEME
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(a) (i) What is meant by the term threshold stimulus?
[1]
The diagram below shows a recording of an action potential passing along a
nerve axon.
e in
tensity of stimulus needed to get a nerve impulse generat
Resting.
brane becomes permeable to sodium ions and they rush in.
inside becomes positively charged.
Need minimum
Not precise enough, need reference to action potential.
It isnt instantaneous
A wasted mark. The student clearly knows what is going on
but isnt answering the questions carefully enough.
(ii) By means of an arrow, indicate on the diagram the probable time when the
stimulus was applied. [1]
(iii) What is the state of the axon membrane from A to B?
[1]
(b) (i) Explain the changes that are occurring in the axon during the period B to D.
[2]
Why?
So what? Need to mention diffusiongradient. This is a good example of a student throwing marks away.
MP 1Total 1 out of 5
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A2 Biology Exam DoctorNERVOUS COORDINATION
QUESTION 2
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(a) (i) Why do synaptic knobs contain many mitochondria?
[2]
The diagram below illustrates the structure of a cholinergic synapse between a
voluntary motor nerve ending and the sarcolemma of a striated muscle fibre.
(ii) Briefly describe how the arrival of an impulse at the synapse causes
depolarisation of the post-synaptic membrane.
[5]
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(a) (i) Why do synaptic knobs contain many mitochondria?
[2]
The diagram below illustrates the structure of a cholinergic synapse between a
voluntary motor nerve ending and the sarcolemma of a striated muscle fibre.
(ii) Briefly describe how the arrival of an impulse at the synapse causes
depolarisation of the post-synaptic membrane.
[5]
To make ATP to provide energy for makingtransmitter substances like acetylcholine.
The vesicles release their transmittersubstances (acetylcholine) out of the pre-synaptic membrane. The acetylcholinediffuses across the gap and causes the
membrane the sarcolemma to change.If there is enough acetylcholine the
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(a)(i) provide ATP;
to provide energy for active absorption of acetate/choline into the knobs;
for combining acetate and choline/to make acetylcholine/synthesis of
acetylcholine; max 2
(ii) calcium ions enter synaptic knobs;
and attract vesicles to the pre-synaptic membrane;
these fuse with the membrane and release acetylcholine;
this attaches to receptors on post synaptic membrane;
making it become permeable to sodium ions;
these rush into the muscle fibre along the concentration gradient;
this alters the potential across the sarcolemma/membrane resulting in an action
potential; max 5
TOTAL 7
MARK SCHEME
(a) (i) Why do synaptic knobs contain many mitochondria? [2]
The diagram below illustrates the structure of a cholinergic synapse between a
voluntary motor nerve ending and the sarcolemma of a striated muscle fibre.
(ii) Briefly describe how the arrival of an impulse at the synapse causesdepolarisation of the post-synaptic membrane. [5]
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Good concise answer with two
separate points well made.
The student
has forgotten,
or does not
know about
the role of
calcium ions
Great! But how?
Lacking in detailhere, they fuse with
the membrane
MP 1
Total 2 out of 7
The diagram below illustrates the structure of a cholinergic synapse between a
voluntary motor nerve ending and the sarcolemma of a striated muscle fibre.
(a) (i) Why do synaptic knobs contain many mitochondria?
[2]
To make ATP to provide energy for makingtransmitter substances like acetylcholine.
The vesicles release their transmittersubstances (acetylcholine) out of the pre-synaptic membrane. The acetylcholinediffuses across the gap and causes the
membrane the sarcolemma to change.If there is enough acetylcholine the
(ii) Briefly describe how the arrival of an impulse at the synapse causes
depolarisation of the post-synaptic membrane.
[5]
MP 3
Too vague!Questions on this topic demand precise detail, vaguedescriptions of membranes changing are no use.
Disappointing after a
good start.
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A2 Biology Exam DoctorNERVOUS COORDINATION
QUESTION 3
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Read through the following passage on neurones and nerve impulses and then fill in the spaces
with the most appropriate word or words.
The nervous system contains several types of neurones. neurones carry
impulses to muscles and glands but neurones carry impulses from
receptors to the central nervous system. The interior of a resting nerve fibre has a lower
concentration of ions than its surroundings, due to the actions of a
in its membrane. This leads to a resting potential on the
inside relative to the outside. Depolarisation occurs when the membrane permeability is
changed by a allowing ions to flood in. If the depolarisation
reaches a value it is propagated along the fibre as an . In some
fibres an insulating layer of allows the depolarisation to jump betweenmaking impulse transmission much . Impulses are propagated across synapses by
release of from vesicles in the synaptic knobs. This release is triggered by
an inflow of ions. [14]
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Read through the following passage on neurones and nerve impulses and then fill in the spaces
with the most appropriate word or words.
The nervous system contains several types of neurones. neurones carry
impulses to muscles and glands but neurones carry impulses from
receptors to the central nervous system. The interior of a resting nerve fibre has a lower
concentration of ions than its surroundings, due to the actions of a
in its membrane. This leads to a resting potential on the
inside relative to the outside. Depolarisation occurs when the membrane permeability is
changed by a allowing ions to flood in. If the depolarisation
reaches a value it is propagated along the fibre as an . In some
fibres an insulating layer of allows the depolarisation to jump betweenmaking impulse transmission much . Impulses are propagated across synapses by
release of from vesicles in the synaptic knobs. This release is triggered by
an inflow of ions. [14]
Motor
sensory
sodium
pump
large
stimulus
potassium
critical
axonpotentialmylin
nodesquicker
hormonessodium
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Read through the following passage on neurones and nerve impulses and then fill in the spaces
with the most appropriate word or words.
The nervous system contains several types of neurones. neurones carry
impulses to muscles and glands but neurones carry impulses from
receptors to the central nervous system. The interior of a resting nerve fibre has a lower
concentration of ions than its surroundings, due to the actions of a
in its membrane. This leads to a resting potential on the
inside relative to the outside. Depolarisation occurs when the membrane permeability is
changed by a allowing ions to flood in. If the depolarisation
reaches a value it is propagated along the fibre as an . In some
fibres an insulating layer of allows the depolarisation to jump betweenmaking impulse transmission much . Impulses are propagated across synapses by
release of from vesicles in the synaptic knobs. This release is triggered by
an inflow of ions. [14]
MARK SCHEMEMotor;
sensory;
sodium;
sodium pump; negative;
stimulus; sodium;
threshold; action potential;
myelin; nodes;
faster;
acetylcholine/eq;
calcium;
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Read through the following passage on neurones and nerve impulses and then fill in the spaces
with the most appropriate word or words.
The nervous system contains several types of neurones. neurones carry
impulses to muscles and glands but neurones carry impulses from
receptors to the central nervous system. The interior of a resting nerve fibre has a lower
concentration of ions than its surroundings, due to the actions of a
in its membrane. This leads to a resting potential on the
inside relative to the outside. Depolarisation occurs when the membrane permeability is
changed by a allowing ions to flood in. If the depolarisation
reaches a value it is propagated along the fibre as an . In some
fibres an insulating layer of allows the depolarisation to jump betweenmaking impulse transmission much . Impulses are propagated across synapses by
release of from vesicles in the synaptic knobs. This release is triggered by
an inflow of ions. [14]
sodium
sensoryMotor
quicker
nodes
stimulus
mylinAccepted wrong spelling.
pump
Specifically need sodium pump.
largeNegative required.
potassium
Sodium
critical
Threshold/minimum value wanted.axonpotential
Action not axon.
hormones
Need acetylcholine/nor-adrenaline/
transmitter substance.
sodium
Calcium ions are involved here.Total 7 out of 14