15. Control and coordination
A section of Biology, 9700
Listing 10 of 130 questions
The passage below outlines how sensory receptors work. Complete the passage by using the most appropriate scientific term. A sensory receptor cell responds to a stimulus by opening ion in its cell surface membrane. Sodium ions flood into the cell causing the membrane to become . This is called the potential. If this potential is large enough to reach a then an action potential is transmitted to the central nervous system. An increase in the strength of the stimulus will result in an increase in the of action potentials transmitted. Describe how an action potential is transmitted along a sensory neurone in a mammal.
9700_s14_qp_41
THEORY
2014
Paper 4, Variant 1
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The passage below outlines how sensory receptors work. Complete the passage by using the most appropriate scientific term. A sensory receptor cell responds to a stimulus by opening ion in its cell surface membrane. Sodium ions flood into the cell causing the membrane to become . This is called the potential. If this potential is large enough to reach a then an action potential is transmitted to the central nervous system. An increase in the strength of the stimulus will result in an increase in the of action potentials transmitted. Describe how an action potential is transmitted along a sensory neurone in a mammal.
9700_s14_qp_43
THEORY
2014
Paper 4, Variant 3
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is a diagram of a sensory neurone and some receptor cells. % & $ ' P\HOLQVKHDWK UHFHSWRUFHOO Name the parts of the neurone labelled A, B, C and D. A B C D Explain how the myelin sheath increases the speed of conduction of nerve impulses. shows the changes in the membrane potential of a sensory neurone when the receptor cells are stimulated. –90 –50 time / ms membrane potential / mV shows the strength of the stimuli applied to these receptor cells. strength of stimulus time / ms With reference to and , describe the relationship between the strength of the stimulus and the resulting action potential.
9700_s16_qp_41
THEORY
2016
Paper 4, Variant 1
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is a diagram of a sensory neurone and some receptor cells. % & $ ' P\HOLQVKHDWK UHFHSWRUFHOO Name the parts of the neurone labelled A, B, C and D. A B C D Explain how the myelin sheath increases the speed of conduction of nerve impulses. shows the changes in the membrane potential of a sensory neurone when the receptor cells are stimulated. –90 –50 time / ms membrane potential / mV shows the strength of the stimuli applied to these receptor cells. strength of stimulus time / ms With reference to and , describe the relationship between the strength of the stimulus and the resulting action potential.
9700_s16_qp_43
THEORY
2016
Paper 4, Variant 3
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is an electron micrograph showing a cross-section of a myelinated neurone. A B Name A and B. A B Explain what is meant by saltatory conduction and describe its effect on the transmission of a nerve impulse. A type of sea snail, Conus purpurascens, produces a toxin that blocks calcium ion channels in the presynaptic knob of a cholinergic synapse. The presence of this toxin results in no action potentials in the postsynaptic neurone. Explain why the presence of this toxin results in no action potentials in the postsynaptic neurone.
9700_s19_qp_42
THEORY
2019
Paper 4, Variant 2
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shows a cholinergic synapse. presynaptic knob B A C D Complete Table 1.1, using the letters A, B, C or D from , to show the location of compounds and structures associated with a cholinergic synapse. You may use A, B, C and D once, more than once, or not at all. Table 1.1 compound or structure location acetylcholine voltage-gated channel receptor protein acetylcholinesterase Explain what is meant by a voltage-gated channel. Explain the role of acetylcholinesterase in a synapse. Outline the roles of synapses in the nervous system.
9700_s19_qp_43
THEORY
2019
Paper 4, Variant 3
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Nerves consist of bundles of different types of neurones. shows the mean transmission speed of impulses for three types of sensory neurone, C, Aδ and Aβ. mean transmission speed of impulse / ms–1 mean axon diameter / μm Aβ C Aδ • Impulses from pain receptors in the skin are sent along sensory neurones C and Aδ. • Sensory neurones C and Aδ synapse in the spinal cord with relay neurones known as projection neurones. • Projection neurones send impulses to the part of the brain that perceives pain. • Impulses from touch receptors in the skin pass along sensory neurones Aβ, which can also synapse with the projection neurones in the spinal cord. • Sensory neurones Aδ and Aβ are myelinated. • Sensory neurones C are unmyelinated. Describe the results shown in and suggest explanations for these results. Gently rubbing a damaged area of skin can reduce the perception of pain. Suggest an explanation for this. Back pain in humans can be reduced by using a transcutaneous electrical nerve stimulation (TENS) machine. A TENS machine uses electrical impulses to stimulate nerve endings near the site of the pain. It is thought that TENS triggers the release of natural painkillers called endorphins at synapses. shows synapses in a pain pathway. endorphin receptor presynaptic knob postsynaptic neurone to pain centre in brain ACh receptor vesicle containing endorphins impulse from area stimulated by TENS machine impulses from area of painful back muscles vesicle containing acetylcholine (ACh) Suggest and explain how endorphins may act to reduce pain. Suggest one disadvantage of using pharmaceutical drugs for reducing pain compared to using TENS.
9700_s21_qp_41
THEORY
2021
Paper 4, Variant 1
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Questions Discovered
130