15.1. Control and coordination in mammals
A subsection of Biology, 9700, through 15. Control and coordination
Listing 10 of 98 questions
shows the concentration of four hormones in a woman’s blood during one menstrual cycle. time / days progesterone oestrogen concentration of hormone in blood / arbitrary units LH FSH With reference to , explain why there is a large increase in LH at around day 12. State how shows that the woman did not become pregnant during this cycle. The combined oral contraceptive pill contains oestrogen and progesterone. Explain how this combined contraceptive pill works to prevent pregnancy. Suggest why some women take the combined contraceptive pill for just the first 21 days of their cycles. Some women have a contraceptive device inserted under the skin. This releases hormones into the blood and can last for up to three years. Suggest one advantage of using such a device rather than taking contraceptive pills.
9700_w16_qp_41
THEORY
2016
Paper 4, Variant 1
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shows the concentration of four hormones in a woman’s blood during one menstrual cycle. time / days progesterone oestrogen concentration of hormone in blood / arbitrary units LH FSH With reference to , explain why there is a large increase in LH at around day 12. State how shows that the woman did not become pregnant during this cycle. The combined oral contraceptive pill contains oestrogen and progesterone. Explain how this combined contraceptive pill works to prevent pregnancy. Suggest why some women take the combined contraceptive pill for just the first 21 days of their cycles. Some women have a contraceptive device inserted under the skin. This releases hormones into the blood and can last for up to three years. Suggest one advantage of using such a device rather than taking contraceptive pills.
9700_w16_qp_42
THEORY
2016
Paper 4, Variant 2
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The Indian cobra (Naja naja) is a species of venomous snake found in South Asia. shows an Indian cobra. The Indian cobra’s venom contains a toxin which causes muscle paralysis in mammals bitten by the snake. The toxin acts at cholinergic synapses. Suggest ways by which the toxin in cobra venom may cause muscle paralysis. Describe the role played by calcium ions in synaptic transmission. Synapses slow down the rate of transmission of nerve impulses but have an important role in the nervous system. Outline two of the roles of synapses in the nervous system.
9700_s15_qp_41
THEORY
2015
Paper 4, Variant 1
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The Indian cobra (Naja naja) is a species of venomous snake found in South Asia. shows an Indian cobra. The Indian cobra’s venom contains a toxin which causes muscle paralysis in mammals bitten by the snake. The toxin acts at cholinergic synapses. Suggest ways by which the toxin in cobra venom may cause muscle paralysis. Describe the role played by calcium ions in synaptic transmission. Synapses slow down the rate of transmission of nerve impulses but have an important role in the nervous system. Outline two of the roles of synapses in the nervous system.
9700_s15_qp_43
THEORY
2015
Paper 4, Variant 3
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Most reflex arcs pass through the spinal cord and involve different types of neurones. Name and state the functions of the three types of neurone in a spinal reflex arc. Some poisons affect the functioning of synapses between neurones. Listed below are four organisms, A, B, C and D, each of which produces a different poison that affects the functioning of synapses. A Hapalochlaena lunulata, the blue-ringed octopus B Conus textile, the textile cone sea snail C Clostridium botulinum, a bacterium D Physostigma venenosum, the calabar bean plant Table 7.1 summarises the action of the poisons from organisms A, B, C and D. Table 7.1 source of poison action of poison at synapse A blocks sodium channels B blocks calcium channels C prevents exocytosis D inhibits acetylcholinesterase
9700_m17_qp_42
THEORY
2017
Paper 4, Variant 2
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is a diagram representing a synapse between a chemoreceptor cell from a human taste bud and a dendrite of a sensory neurone. microvilli chemoreceptor cell synapse dendrite of sensory neurone In an experiment, different concentrations of sodium chloride solution were applied to the microvilli of the chemoreceptor cell. The membrane potential of the chemoreceptor cell and the membrane potential of the dendrite of the sensory neurone were recorded for each concentration. The resting potential of this chemoreceptor cell is –50 mV and the resting potential of the dendrite of this sensory neurone is –70 mV. The results are shown in Table 7.1. Table 7.1 concentration of sodium chloride solution / g dm–3 membrane potential / mV chemoreceptor cell dendrite of sensory neurone 0.1 –50 –70 1.0 +30 +40 10.0 +30 +40 Explain the results shown in Table 7.1. Describe the differences in structure and function between sensory neurones and motor neurones.
9700_m23_qp_42
THEORY
2023
Paper 4, Variant 2
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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_41
THEORY
2014
Paper 4, Variant 1
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Questions Discovered
98