Question 1
During the start of a sprint, impulses from the brain stimulate selected leg muscles within milliseconds. What feature makes nervous signalling suited to this role?
A.
Blood transports glucose directly into motor neurons.
B.
Hormones circulate slowly in blood to all body tissues.
C.
Signals travel rapidly along neurons to specific effectors.
D.
Endocrine glands contract to move bones at joints.
Question 2
A goalkeeper improves after practice by combining visual information, balance information and sensory input from muscles before moving to intercept a ball. What role of the brain is illustrated?
A.
Producing epinephrine to increase ventilation rate
B.
Filtering blood to detect changes in water potential
C.
Processing multiple inputs and using learning to coordinate output
D.
Coordinating peristalsis independently of conscious control
Question 3
In a pain-withdrawal reflex, the synapse between a sensory neuron and an interneuron occurs in the region labelled X. What is region X?
A.
Motor cortex
B.
White matter
C.
Protective sheath
D.
Grey matter
Question 4
The graph shows the concentration of melatonin in blood over a 24-hour cycle under normal light-dark conditions. What conclusion is supported by the graph?
A.
Melatonin peaks at midday and stimulates vigorous activity.
B.
Melatonin rises during the night and helps promote sleep readiness.
C.
Melatonin is secreted by adrenal glands after exercise.
D.
Melatonin remains constant because circadian rhythms are external.
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Question 5
A bolus has passed from the pharynx into the oesophagus after swallowing. What mainly coordinates its movement through the digestive tract until near egestion?
A.
Epinephrine secretion from adrenal glands above the kidneys
B.
Involuntary control by the enteric nervous system in the gut wall
C.
Voluntary signals from the cerebral hemispheres throughout the gut
D.
Melatonin secretion from the pineal gland into the bloodstream
Question 6
A shoot grows toward a lamp placed on one side. What causes this positive phototropic curvature?
A.
Cells at the root tip contract and pull the shoot toward the light.
B.
Cells on the shaded side elongate faster than cells on the illuminated side.
C.
Cells on the illuminated side divide faster than cells on the shaded side.
D.
Cells on both sides elongate equally until the shoot reaches the light.
Question 7
A ripe banana is placed in a sealed bag with unripe bananas, and the unripe bananas ripen more rapidly. What explains this effect?
A.
Melatonin from ripe fruit creates a 24-hour cycle of fruit dormancy.
B.
Auxin from ripe fruit diffuses into seeds and stops all cell enlargement.
C.
Cytokinin from ripe fruit lowers oxygen concentration and prevents respiration.
D.
Ethylene from ripening fruit stimulates ripening and further ethylene production.
Question 8
Multicellular organisms have a hierarchy of integrated subsystems.
Define the term tissue.
[1]
Explain how integration of body systems can lead to an emergent property, using movement in an animal as an example.
[2]
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Question 9
Blood pressure rises above its normal range. What response is part of negative feedback control of heart rate?
A.
Chemoreceptors decrease input to the pineal gland, which releases melatonin.
B.
Chemoreceptors stimulate the gut wall, which increases peristalsis.
C.
Baroreceptors increase input to the medulla, which reduces heart rate.
D.
Baroreceptors stimulate the pancreas, which raises blood glucose concentration.
Question 10
A student measures the angle of curvature of seedlings growing toward a lamp. What change would best increase reliability of the results?
A.
Use repeated seedlings of similar age under the same light conditions.
B.
Change the lamp distance for each seedling before measuring.
C.
Use one seedling and record a detailed labelled drawing only.
D.
Measure different seedlings at different times of day without repeats.
Question 11
Auxin efflux carriers become concentrated on the same side of many neighbouring shoot cells. What is the effect of this polar placement?
A.
Auxin is actively transported in one direction, forming a tissue gradient.
B.
Auxin diffuses freely out of all cell surfaces at equal rates.
C.
Ethylene is trapped inside cell walls and prevents shoot growth.
D.
Cytokinin is converted into auxin in the apoplast of every cell.
Question 12
What sequence describes the promotion of cell elongation by auxin in shoot cells?
A.
Ethylene enters the nucleus, chromosomes shorten and mitosis bends the shoot.
B.
Hydrogen ions leave the apoplast, wall pH rises, cellulose hardens and the cell contracts.
C.
Hydrogen ions enter the apoplast, wall pH falls, cross-links loosen and turgor stretches the cell.
D.
Cytokinin breaks cellulose microfibrils, water leaves the vacuole and the cell shrinks.
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Question 13
A gardener removes the shoot tip of a young plant and lateral buds begin to grow more strongly. What hormonal explanation is most consistent with this observation?
A.
Melatonin from leaves increases, converting roots into lateral shoots.
B.
Auxin from the shoot tip falls, reducing inhibition of lateral buds while cytokinin promotes growth.
C.
Ethylene from roots stops ripening, causing new leaves to form on lateral buds.
D.
Cytokinin from the shoot tip rises, preventing all lateral buds from developing.
Question 14
Animal organs are integrated by nervous signalling, hormonal signalling and transport in blood.
Compare nervous signalling and hormonal signalling in animals.
[2]
Outline two roles of blood in the integration of organs.
[2]
Question 15
The diagram shows a transverse section of a peripheral nerve.
State the feature shown by X that encloses the nerve fibres.
[1]
Distinguish between the fibres labelled Y and Z.
[1]
Explain why a peripheral nerve can carry information both to and from the central nervous system.
[1]
Question 16
The graph shows the concentration of melatonin in the blood of a human over a 24-hour period under a normal light-dark cycle.
State the gland that secretes melatonin.
[1]
Describe the diurnal pattern of melatonin secretion shown by the graph.
[1]
Explain how this pattern helps to establish a cycle of sleeping and waking.
[2]
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Question 17
Seedlings of the same species were grown with light from one side. Observations were recorded after two days.
Seedling | Shoot appearance after 2 days | Shoot curvature / |
|---|---|---|
1 | slightly curved toward lamp | 16 |
2 | curved toward lamp | 19 |
3 | moderately curved toward lamp | 21 |
4 | curved toward lamp | 18 |
5 | strongly curved toward lamp | 23 |
Distinguish between a qualitative observation and a quantitative observation in this investigation.
[2]
Suggest one method to improve the reliability of the investigation.
[1]
State the tropic response shown by shoots grown with light from one side.
[1]
Question 18
A shoot tip is illuminated from one side.
State which side of the shoot elongates faster during positive phototropism.
[1]
Explain how lateral light causes the shoot to curve toward the light.
[2]
Suggest one advantage of positive phototropism to a seedling.
[1]
Question 19
A student compared the timing and distribution of two types of communication involved in preparing leg muscles for a sprint.
Communication method | Transport medium | Time to first detectable response / s | Responding cells/tissues |
|---|---|---|---|
Motor neurone signal | Nervous tissue (axon and synapse) | 0.2 | Localised to one leg muscle group |
Adrenaline signal | Blood plasma | 10 | Widely distributed; only target cells with receptors respond |
Identify the signalling method that gives the shortest time to first detectable response.
[1]
Compare the specificity of the two signalling methods shown in the table.
[1]
Explain why both signalling and blood transport are needed for intense contraction of leg muscles during a sprint.
[2]
Question 20
Seedlings of the same species were grown with a lateral light source. Their shoots were photographed at regular intervals and the angle of curvature was measured from the vertical.
Time / h | Shoot appearance | Curvature angle from vertical / |
|---|---|---|
0 | shoot straight; no visible bend | 0 |
2 | slight bend toward light | 9 |
4 | clear bend toward light | 19 |
6 | more pronounced bend toward light | 32 |
8 | strong bend toward light | 47 |
Distinguish between the qualitative and quantitative observations in the stimulus.
[2]
State the tropic response shown by the shoots.
[1]
Suggest one change to the method that would increase reliability of the mean curvature angle.
[1]
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Question 21
Touching a hot surface can cause the hand to be withdrawn before the person becomes fully aware of the pain.
State the type of receptor that detects the damaging stimulus in the skin.
[1]
Explain how the withdrawal response is coordinated by the spinal cord.
[3]
Question 22
During vigorous exercise, muscle cells produce more . This affects blood pH and ventilation rate.
State the receptors that monitor changes in blood pH involved in ventilation control.
[1]
Explain why ventilation rate increases when blood concentration rises.
[2]
Identify the type of feedback involved when increased ventilation restores blood pH toward normal.
[1]
Question 23
Auxin efflux carriers can be positioned on one side of cells in plant tissue.
Define the term phytohormone.
[1]
Explain how auxin efflux carriers can create a concentration gradient of auxin in plant tissue.
[3]
Question 24
Auxin promotes elongation of cells in young shoots.
State the part of the plant cell outside the plasma membrane that becomes acidified during auxin-stimulated growth.
[1]
Explain how auxin promotes cell elongation.
[3]
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Question 25
Auxin and cytokinin help integrate root and shoot growth in plants.
State the main sites of production of auxin and cytokinin in a young plant.
[2]
Explain how auxin and cytokinin can act antagonistically in the control of lateral bud growth.
[2]
Question 26
A ripe banana is placed in a closed bag with several unripe bananas. The unripe bananas ripen more rapidly than similar bananas kept separately.
State the gaseous phytohormone responsible for stimulating fruit ripening.
[1]
Explain why placing ripe and unripe fruit together can accelerate ripening.
[2]
Identify the type of feedback involved and state its consequence for a group of fruits.
[1]
Question 27
The figure shows recordings made during a hand-withdrawal reflex after a finger touched a hot surface. Electrodes recorded impulses in three neurons in the reflex pathway.
State which recorded neuron carried impulses into the central nervous system.
[1]
Deduce the location of the interneuron involved in this reflex.
[1]
Explain why the hand begins to withdraw before conscious pain perception is indicated.
[2]
Question 28
A transverse section of a peripheral nerve was examined using a light microscope. Some regions were labelled by the student.
State the function of the structure labelled A.
[1]
Distinguish between the fibres labelled B and C.
[1]
Suggest why damage to this nerve could affect both sensation from the skin and contraction of a muscle in the same region.
[2]
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Question 29
Melatonin concentration in blood was measured in volunteers over one normal light-dark cycle and again when bright light was used during the late evening.
Describe the diurnal pattern of melatonin secretion under normal conditions.
[1]
State the gland that secretes melatonin.
[1]
Explain how bright light late in the evening could alter the sleep-wake cycle.
[2]
Question 30
A coleoptile shoot was exposed to light from one side. Cell lengths were measured on the illuminated side and shaded side after several hours.
Describe the difference in cell elongation shown in the bar chart.
[1]
Explain how this difference in cell elongation causes the shoot to bend toward the light.
[2]
Suggest one advantage of positive phototropism for a seedling.
[1]
Question 31
A subject moved rapidly from lying down to standing. Blood pressure, baroreceptor impulse frequency and heart rate were monitored for the next minute.
Describe the change in heart rate immediately after the fall in blood pressure.
[1]
Identify the receptors that detect the fall in blood pressure and state one location where they are found.
[2]
Explain why the response shown is negative feedback.
[2]
Question 32
Ventilation was recorded before, during and after moderate exercise. Blood concentration and blood pH were measured at the same times.
Stage | Ventilation rate / L min | Blood concentration / mmol dm | Blood pH |
|---|---|---|---|
Before exercise | 6.0 | 2.4 | 7.41 |
During exercise | 18.0 | 3.1 | 7.33 |
After exercise | 8.0 | 2.5 | 7.39 |
Describe the change in ventilation rate during exercise.
[1]
Explain the link between increased production and the change in blood pH.
[2]
Evaluate the evidence that ventilation rate is controlled by negative feedback in this recording.
[2]
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Question 33
Researchers used fluorescent markers to show the position of auxin efflux carriers in a row of shoot cells. Auxin concentration was then measured across the tissue.
Identify the cell structure in which the auxin efflux carriers are positioned.
[1]
Deduce how the polar distribution of efflux carriers affects auxin movement through the tissue.
[2]
Explain why auxin can enter plant cells more readily than it can leave without efflux carriers.
[2]
Question 34
Segments of young shoot tissue were placed in solutions containing different auxin concentrations. Apoplast pH and increase in segment length were measured after incubation.
Auxin concentration / nM | Mean apoplast pH | Mean increase in length / mm |
|---|---|---|
0 | 6.5 | 0.8 |
1 | 6.3 | 1.1 |
10 | 6.0 | 1.7 |
100 | 5.5 | 2.9 |
1000 | 4.9 | 4.8 |
Describe the relationship between apoplast pH and segment elongation shown in the data.
[1]
Explain how auxin promotes elongation of shoot cells.
[3]
Suggest how an auxin concentration gradient across a shoot could lead to phototropic curvature.
[1]
Question 35
Unripe bananas were stored either alone or in a sealed container with one ripe banana. Ethylene concentration and ripeness score were recorded over several days.
Time / d | Ethylene / ppm (alone) | Ripeness score (alone) | Ethylene / ppm (with ripe banana) | Ripeness score (with ripe banana) |
|---|---|---|---|---|
0 | 0.10 | 1 | 0.80 | 1 |
1 | 0.10 | 1 | 1.60 | 2 |
2 | 0.20 | 2 | 3.20 | 3 |
3 | 0.20 | 2 | 5.20 | 4 |
4 | 0.30 | 3 | 7.40 | 5 |
Describe the effect of storing unripe bananas with a ripe banana on ripening.
[1]
Explain why ethylene from the ripe banana can affect nearby unripe bananas.
[2]
Explain why the relationship between ethylene production and fruit ripening is positive feedback and suggest one benefit to the plant.
[2]
Question 36
During a sprint, skeletal muscles require rapid changes in oxygen supply, glucose supply and nervous control. Several body systems must function as an integrated system.
I.
Outline what is meant by system integration in a multicellular organism.
[1]
II.
Describe one emergent property that results from integration of body systems during sprinting.
[2]
Compare nervous and hormonal signalling in the integration of organs during vigorous activity.
[2]
Discuss the role of blood transport in allowing the signalling systems to produce an effective response.
[2]
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Question 37
A traveller crosses several time zones and then participates in a sports event the next morning. Hormonal signalling contributes both to sleep regulation and to preparation for vigorous activity.
I.
Explain the diurnal pattern of melatonin secretion and its effect on sleep.
[2]
II.
Suggest why exposure to bright light late at night may shift sleep patterns.
[1]
Explain how epinephrine secretion prepares the body for intense muscle contraction.
[3]
Discuss how the hypothalamus and pituitary gland illustrate integration between the nervous and endocrine systems.
[1]
Question 38
Movement of food through the digestive tract involves both voluntary control and involuntary coordination. A mixed spinal nerve also contains fibres carrying information in opposite directions.
I.
Identify two features visible in a transverse section of a nerve.
[2]
Explain why many nerves contain both sensory and motor fibres.
[2]
Compare and contrast control of swallowing, peristalsis between swallowing and egestion, and egestion of faeces.
[2]
Question 39
Seedlings of the same species are placed in boxes with a light source at one side. Observations are made over two days to investigate tropic responses.
I.
Distinguish between qualitative and quantitative observations that could be collected in this investigation.
[2]
II.
State the tropic response shown by shoots growing toward unilateral light.
[1]
Evaluate two factors that could limit the precision or accuracy of measuring curvature angle.
[2]
Suggest two improvements that would increase the reliability of the investigation.
[2]
Question 40
Shoot tips were removed from young plants. Some cut shoots received an auxin paste on the cut surface, while others received no paste. Cytokinin concentration in lateral buds was also measured.
Shoot treatment | Mean lateral shoot growth / mm | Cytokinin concentration in lateral buds / a.u. |
|---|---|---|
Intact shoot tip | 3.2 | 3.0 |
Shoot tip removed | 13.6 | 8.2 |
Shoot tip removed + auxin paste | 4.4 | 4.1 |
State the effect of removing the shoot tip on lateral shoot growth.
[1]
Explain how the auxin paste treatment supports the role of auxin in apical dominance.
[2]
Evaluate whether the data show antagonistic interaction between auxin and cytokinin in regulating shoot growth.
[2]
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Question 41
A person accidentally touches a very hot metal surface with one hand and rapidly withdraws the hand before consciously identifying the object.
I.
State the type of receptor involved in detecting the damaging stimulus in the skin.
[1]
II.
Outline the sequence of neurons involved in the withdrawal reflex.
[2]
Explain why withdrawal can begin before the person consciously identifies the object.
[3]
Discuss how the brain and cerebellum could contribute after the initial reflex withdrawal.
[2]
Question 42
The graph shows changes in arterial blood pressure and heart rate in a person who stands up rapidly after lying down. The initial fall in blood pressure is followed by recovery.
I.
Identify the receptors that detect the initial fall in blood pressure and state their location.
[2]
II.
State the part of the brainstem that coordinates the response.
[1]
Explain how the changes shown in the graph are produced by negative feedback.
[3]
Evaluate why chemoreceptor input may also affect heart rate during prolonged vigorous exercise.
[2]
Question 43
A volume-time trace from a breathing monitor is recorded before and after a short period of running.
I.
Describe two changes in the trace after exercise.
[2]
Explain the feedback mechanism that causes ventilation rate to change after exercise.
[3]
Discuss why this control system is described as negative feedback.
[2]
Question 44
A shoot tip is exposed to lateral light. Auxin distribution across the shoot changes before the shoot bends.
I.
State what is meant by a phytohormone and give one example involved in phototropism.
[2]
II.
Explain why auxin efflux carriers are needed to maintain an auxin gradient.
[1]
Explain how coordinated positioning of auxin efflux carriers produces curvature toward light.
[3]
Discuss why positive phototropism can increase the survival of a seedling.
[2]
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Question 45
In an experiment, one side of a young shoot contains a higher concentration of auxin than the other side.
I.
Define the apoplast.
[1]
II.
State the immediate effect of auxin on hydrogen ion movement.
[1]
Explain how auxin promotes elongation of shoot cells.
[3]
Explain how an auxin concentration gradient leads to bending of a shoot in phototropism.
[2]
Question 46
Gardeners often remove the shoot tips of young plants to encourage a bushier form. Root and shoot growth are regulated by interactions between auxin and cytokinin.
I.
State where auxin and cytokinin are produced in the plant and the direction in which each is transported.
[2]
II.
Define an antagonistic interaction between hormones.
[1]
Explain how removing the shoot tip can increase growth of lateral shoots.
[2]
Discuss why integration of root and shoot growth is important for the whole plant.
[2]
Question 47
Unripe fruit are stored either alone or with ripe fruit in sealed containers. Ripening occurs more rapidly in the containers that include ripe fruit.
I.
Name the gaseous phytohormone involved in fruit ripening.
[1]
II.
State one change that occurs during fruit ripening.
[1]
Explain how ethylene and fruit ripening form a positive feedback mechanism.
[3]
Evaluate the biological benefit of synchronized fruit ripening.
[2]
Question 48
Plants and animals both integrate body systems using signalling chemicals, but the outcomes and mechanisms can differ. In plants, auxin, cytokinin and ethylene are examples of phytohormones.
I.
Outline two roles of phytohormones in plants.
[2]
II.
Give one example of a phytohormone and its associated response.
[1]
Compare and contrast the way auxin and ethylene can coordinate responses across plant tissues.
[3]
Discuss why chemical signalling alone is sufficient for many plant responses, whereas animals often also require nervous signalling.
[2]
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