Question 1
What feature of capillary networks most directly increases the total surface area available for exchange with tissues?
A.
Branching into many narrow vessels
B.
Valves positioned along the vessel
C.
Elastic recoil after each heartbeat
D.
Presence of thick smooth muscle layers
Question 2
A transverse section through two human blood vessels is shown. What visible feature identifies vessel X as a vein?
A.
Rounded outline with elastic tissue layers
B.
Wall adapted to withstand high pressure
C.
Thin wall relative to a wide lumen
D.
Thick wall relative to a narrow lumen
Question 3
What is the role of elastic tissue in the walls of arteries?
A.
It stretches during ventricular contraction and recoils to maintain blood pressure.
B.
It makes the artery wall one cell thick for rapid diffusion.
C.
It forms pocket valves that prevent blood flowing backwards.
D.
It actively contracts to narrow the lumen during vasoconstriction.
Question 4
What arrangement of tissues is typical of a transverse section of a young dicotyledonous root?
A.
Phloem towards the inside of each bundle and xylem towards the outside
B.
Star-shaped central xylem with phloem between the arms
C.
Scattered vascular bundles throughout the cortex and pith
D.
Vascular bundles arranged in a ring near the outer stem region
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Question 5
What causes plasma to leave capillaries and form tissue fluid at the arteriole end of a capillary bed?
A.
Red blood cells diffuse out through fenestrations and carry water with them.
B.
Low venous pressure actively pumps plasma proteins into surrounding tissues.
C.
Relatively high blood pressure forces fluid through gaps in the capillary wall.
D.
Valves in capillaries close and squeeze fluid into the tissue spaces.
Question 6
What adaptation of lymph ducts helps return excess tissue fluid to the blood circulation at low pressure?
A.
Thick elastic walls that recoil between ventricular contractions
B.
Fenestrated walls that retain all water but release plasma proteins
C.
Thin walls with gaps for fluid entry and valves to prevent backflow
D.
Large smooth muscle layers that generate systolic blood pressure
Question 7
Why is the wall of the left ventricle thicker than the wall of the right ventricle in a mammalian heart?
A.
It must receive blood returning from all tissues through the vena cava.
B.
It must pump blood to the lungs at low pressure for gas exchange.
C.
It must prevent blood flowing back from the aorta into the atrium.
D.
It must generate higher pressure to pump blood through the systemic circulation.
Question 8
Capillary beds are found close to active tissues, such as the epithelium of the small intestine.
State one function of capillaries in tissues.
[1]
Explain how two structural adaptations of capillaries increase the rate of exchange.
[2]
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Question 9
A student compared heart rate estimated by counting a radial pulse with heart rate measured using a pulse oximeter.
Trial | Radial pulse / beats min | Pulse oximeter / beats min |
|---|---|---|
1 | 72 | 73 |
2 | 75 | 74 |
3 | 73 | 73 |
4 | 74 | 72 |
5 | 71 | 73 |
State why the thumb should not be used when measuring a radial pulse by touch.
[1]
Suggest two controls that would make the comparison between the two methods fair.
[2]
Explain why repeated trials improve the reliability of pulse-rate measurements.
[1]
Question 10
A student compares heart rate measured by counting the radial pulse with heart rate measured by a pulse oximeter. What procedure gives the fairest comparison of the two methods?
A.
Use the thumb to locate the pulse and record one measurement from each method.
B.
Use different people for each method and compare the highest readings obtained.
C.
Use the same person, same posture and repeated measurements taken at similar times.
D.
Count the pulse for after exercise and compare it with a resting oximeter value.
Question 11
What explains the upward movement of water in xylem during active transpiration?
A.
Root cells pump water molecules directly into xylem vessels by active transport.
B.
Companion cells actively transport water upward through sieve tubes using ATP.
C.
Arterial pressure forces water through lignified vessels towards the leaves.
D.
Evaporation from leaf cell walls generates tension that is transmitted through cohesive water columns.
Question 12
What is an advantage of the mammalian double circulation compared with the single circulation of a bony fish?
A.
Blood passes through the heart once during a complete circuit of the body.
B.
Oxygenated and deoxygenated blood mix before leaving the ventricle.
C.
Blood flows from the heart to gills before passing to body tissues.
D.
Systemic blood can be pumped at high pressure while pulmonary blood is kept at lower pressure.
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Question 13
What adaptation allows sieve tube elements to function despite having no nucleus at maturity?
A.
Lignified end walls prevent collapse under xylem tension.
B.
Fenestrations in the wall allow red blood cells to pass through.
C.
Companion cells connected by plasmodesmata provide metabolic support.
D.
A pacemaker initiates rhythmic contractions of the sieve tube.
Question 14
The micrograph shows transverse sections of two blood vessels from the same region of a mammal. Vessel X and vessel Y are shown at the same magnification.
Identify the type of blood vessel represented by X.
[1]
Distinguish between arteries and veins using two visible features in transverse section.
[2]
Outline the role of elastic tissue in artery walls.
[1]
Question 15
Water can move from roots to leaves through xylem vessels in a tall transpiring plant.
Define transpiration.
[1]
Explain how evaporation from leaf cell walls causes water to move upward in xylem.
[2]
State the role of cohesion in xylem transport.
[1]
Question 16
Excess tissue fluid in the legs can enter lymph ducts and eventually return to the blood circulation.
State what lymph is.
[1]
Explain how two adaptations of lymph ducts help return excess tissue fluid to the blood.
[2]
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Question 17
The table shows structural features of capillaries from three mammalian tissues and a measured rate of movement of small solutes across the capillary wall.
Tissue | Wall structure | Fenestrations | Branching density | Small-solute movement / arbitrary units |
|---|---|---|---|---|
Kidney (glomerulus) | one cell thick endothelium + basement membrane | present | high | 8 |
Skeletal muscle | one cell thick endothelium + basement membrane | absent | medium | 3 |
Brain | one cell thick endothelium + basement membrane | absent | low | 1 |
Identify the tissue in which capillaries are most adapted for rapid filtration.
[1]
Explain how two capillary features shown in the table increase exchange between blood and surrounding tissues.
[2]
Suggest why red blood cells and most plasma proteins are not lost from these capillaries during exchange.
[1]
Question 18
The micrograph shows transverse sections of two blood vessels, labelled X and Y, taken from the same region of a mammal. Measurements of wall thickness and lumen diameter are shown beside the micrograph.
Identify vessel X as an artery or a vein.
[1]
Explain the evidence from the micrograph and measurements for your answer in part (a).
[2]
Suggest how elastic tissue in the wall of vessel X helps maintain blood flow.
[1]
Question 19
A student compared pulse rate measured by fingertip counting at the radial artery with values from a pulse oximeter. Measurements were made at rest and immediately after two minutes of step exercise.
Condition | Trial | Fingertip count / pulses in 30 s | Pulse oximeter / beats min |
|---|---|---|---|
Rest | 1 | 36 | 72 |
Rest | 2 | 34 | 72 |
Rest | 3 | 39 | 73 |
After 2 min step exercise | 1 | 60 | 120 |
After 2 min step exercise | 2 | 64 | 121 |
After 2 min step exercise | 3 | 58 | 120 |
The first resting fingertip count was 36 pulses in 30 s. Calculate the heart rate in beats min.
[1]
Compare the reliability of the two methods using the repeated measurements.
[2]
Suggest one change to the procedure that would make the comparison between the two methods fairer.
[1]
Question 20
The graph shows pressure changes in the left atrium, left ventricle and aorta during one cardiac cycle. At what point does the aortic semilunar valve open?
A.
When left atrial pressure first exceeds left ventricular pressure
B.
When left ventricular pressure first exceeds aortic pressure
C.
When aortic pressure first exceeds left ventricular pressure
D.
When left ventricular pressure first falls below left atrial pressure
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Question 21
Epidemiologists investigated the relationship between mean saturated fat intake and death rate from coronary heart disease in several populations.
Describe the relationship shown in the graph.
[1]
Outline how occlusion of a coronary artery can lead to myocardial infarction.
[2]
Evaluate whether the graph alone proves that saturated fat intake causes coronary heart disease.
[1]
Question 22
The image shows a transverse section of a young dicotyledonous root.
Draw a plan diagram of the root section and label the epidermis, cortex, xylem and phloem.
[3]
State one feature visible in the section that identifies it as a root rather than a stem.
[1]
Question 23
The diagram represents a capillary bed between an arteriole and a venule.
State the process by which tissue fluid is formed at the arteriole end of a capillary bed.
[1]
Explain why tissue fluid has a different composition from blood plasma.
[2]
Outline why some tissue fluid drains back into capillaries at the venule end.
[1]
Question 24
The diagrams show simplified circulation pathways in a bony fish and in a mammal.
Compare the pathway of blood in single circulation in bony fish with double circulation in mammals.
[2]
Explain two advantages of double circulation in mammals.
[2]
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Question 25
The diagram shows a frontal section of a mammalian heart.
Trace the pathway of blood from the vena cava to the aorta through the heart.
[2]
Explain how two named heart structures help deliver pressurized blood to arteries.
[2]
Question 26
A leafy shoot was placed in a potometer. The rate of water uptake and the pressure potential in xylem were measured under different relative humidities while light intensity and temperature were kept constant.
Relative humidity / % | Water uptake / | Xylem pressure potential / MPa |
|---|---|---|
20 | 16.5 | |
40 | 12.4 | |
60 | 8.1 | |
80 | 4.2 | |
90 | 2.1 |
Describe the effect of increasing relative humidity on water uptake by the shoot.
[1]
Explain how transpiration can generate tension in xylem vessels.
[2]
State one adaptation of xylem vessels that helps them transport water under tension.
[1]
Question 27
The figure shows low-power transverse sections from a young dicotyledonous stem and a young dicotyledonous root. Several tissue regions are labelled.
Distinguish the stem from the root using the distribution of vascular tissue shown in the figure.
[2]
Identify the labelled tissue that transports dissolved organic compounds such as sucrose.
[1]
State the main function of the labelled cortex in these sections.
[1]
Question 28
Samples of blood plasma and tissue fluid were collected from the same tissue. Concentrations of selected components are shown in the table. The tissue was actively respiring during the sampling period.
Component | Unit | Blood plasma | Tissue fluid |
|---|---|---|---|
Blood cells | cells mm | 0 | |
Plasma proteins | g dm | 70 | 5 |
Water | % | 91 | 94 |
Glucose | mmol dm | 5.0 | 5.0 |
Amino acids | mmol dm | 2.0 | 2.0 |
Mineral ions | mmol dm | 145 | 145 |
Oxygen | mmol dm | 0.20 | 0.12 |
Carbon dioxide | mmol dm | 2.2 | 2.6 |
Compare the composition of plasma and tissue fluid using the table.
[2]
Explain the direction of diffusion of oxygen and carbon dioxide between tissue fluid and actively respiring cells.
[2]
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Question 29
The diagrams show the circulation of a bony fish and a mammal. A graph below each diagram shows relative blood pressure in the main parts of the circuit.
Identify which diagram shows single circulation.
[1]
Compare the route of blood through the heart in the two circulatory systems.
[2]
Explain one advantage of the mammalian pressure pattern shown in the graph.
[1]
Question 30
The graph shows pressure changes in the left atrium, left ventricle and aorta during one cardiac cycle.
State the pressure relationship that causes the aortic semilunar valve to open.
[1]
Explain why the left atrioventricular valve closes during early ventricular systole.
[1]
Explain how systolic and diastolic blood pressures are obtained from the aortic pressure curve.
[2]
Question 31
Pressure differences contribute to transport in plants. Root pressure can move xylem sap when transpiration is low, and pressure flow can move phloem sap from sources to sinks.
Explain how root pressure is generated in xylem vessels.
[2]
Explain how sieve tube elements and companion cells are adapted for translocation of phloem sap.
[2]
Question 32
Epidemiological data were collected from several populations. The graph compares mean saturated fat intake with mortality from coronary heart disease. A table beside the graph gives correlation coefficients for several possible risk factors.
Population | Mean saturated fat intake / % energy | CHD mortality / per 100 000 | Risk factor | Correlation coefficient () |
|---|---|---|---|---|
Japan | 7.0 | 45 | — | — |
Greece | 8.5 | 52 | — | — |
Spain | 10.0 | 70 | — | — |
UK | 12.0 | 92 | — | — |
USA | 14.0 | 118 | — | — |
Finland | 16.0 | 145 | — | — |
— | — | — | Mean age | 0.80 |
— | — | — | Mean blood pressure | 0.84 |
— | — | — | Saturated fat intake | 0.97 |
— | — | — | Serum cholesterol | 0.86 |
— | — | — | Smoking prevalence | 0.89 |
State which variable provides the strongest evidence of association with coronary heart disease mortality.
[1]
Explain how occlusion of a coronary artery can lead to death of cardiac muscle tissue.
[2]
Evaluate the conclusion that saturated fat intake causes coronary heart disease, using the data.
[2]
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Question 33
Pressures were measured along a systemic capillary bed from the arteriole end to the venule end. The graph shows blood hydrostatic pressure and the opposing osmotic effect of plasma proteins.
Identify where tissue fluid is formed and where it is reabsorbed along the capillary bed.
[2]
Explain why most plasma proteins remain in the blood as tissue fluid forms.
[1]
Suggest how increased arterial blood pressure could affect tissue fluid formation.
[1]
Question 34
A researcher investigated the effect of impaired lymph drainage on fluid accumulation in a mammalian limb. The diagram shows lymph vessels in the tissue and the graph shows change in limb circumference over time.
State the evidence from the graph that impaired lymph drainage caused oedema.
[1]
Explain how two features of lymph vessels shown in the diagram allow excess tissue fluid to be returned to the blood.
[2]
Suggest why valves are especially important in lymph vessels.
[1]
Question 35
A tissue with a high rate of aerobic respiration is supplied by a dense capillary network. The capillaries in part of the tissue are fenestrated.
I.
State the type of tissue that forms the wall of a capillary.
[1]
II.
Explain how branching of capillaries improves exchange with the surrounding tissue.
[2]
Explain how the structure of the capillary wall allows exchange but limits loss of blood components.
[2]
Discuss why fenestrated capillaries would be advantageous in a tissue where rapid filtration is required.
[2]
Question 36
The micrograph shows transverse sections of two blood vessels from the same mammal.
I.
Identify which vessel is the artery, using one visible feature.
[1]
II.
State two structural features expected in the wall of an artery.
[2]
Compare and contrast how the artery and vein are adapted to the pressure of the blood they carry.
[3]
Explain why defining an artery as a vessel carrying oxygenated blood would be incorrect.
[2]
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Question 37
The diagram shows blood return from the lower leg through a vein when a person alternately contracts and relaxes skeletal muscles.
I.
State the direction in which veins carry blood relative to the heart.
[1]
II.
State one structural feature of veins that differs from arteries.
[1]
Explain how valves and skeletal muscle contraction contribute to venous return from the legs.
[3]
Suggest why prolonged immobility can increase the risk of slow blood flow in leg veins.
[2]
Question 38
Cells in a respiring tissue exchange substances with tissue fluid rather than directly with blood plasma.
I.
State one component found in plasma at a higher concentration than in tissue fluid.
[1]
II.
State two small dissolved substances that may be present in both plasma and tissue fluid.
[2]
Explain how tissue fluid allows exchange between capillaries and respiring cells.
[3]
Discuss why the composition of tissue fluid changes as it passes through an active tissue.
[2]
Question 39
The graph shows pressure changes in the left atrium, left ventricle and aorta during one cardiac cycle. Points P, Q, R and S mark valve events.
State the systolic and diastolic blood pressures from the aortic pressure curve.
[1]
Using the pressure curves, identify the valve event that occurs when left ventricular pressure first exceeds aortic pressure and the valve event that occurs when aortic pressure later exceeds left ventricular pressure.
[2]
Explain the sequence of events in the left side of the heart after initiation of a heartbeat by the sinoatrial node.
[2]
Question 40
A photosynthesising leaf and a developing fruit were connected by the same phloem pathway. The diagram shows sieve tube elements and companion cells. The table shows sucrose concentration and hydrostatic pressure in phloem at the two locations.
Identify the source and the sink in this investigation.
[1]
Explain how companion cells support translocation in the sieve tube elements.
[2]
Explain how the data support pressure flow of phloem sap from the leaf to the developing fruit.
[2]
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Question 41
Students compared heart rate measured by counting the radial pulse with heart rate measured using a pulse oximeter after light exercise.
Repeat | Manual time after exercise / s | Manual pulse / beats | Oximeter time after exercise / s | Pulse oximeter / beats |
|---|---|---|---|---|
1 | 15 | 132 | 45 | 126 |
2 | 30 | 128 | 60 | 123 |
3 | 45 | 124 | 75 | 120 |
4 | 60 | 121 | 90 | 117 |
I.
State why a pulse can be used to estimate heart rate.
[1]
II.
Describe two precautions for measuring a radial pulse manually.
[2]
Explain why repeated measurements improve the reliability of the comparison.
[2]
Evaluate the design of the comparison between manual pulse counting and a digital pulse oximeter.
[2]
Question 42
A leafy shoot was placed in dry moving air. The rate of water uptake by the shoot increased.
I.
Define transpiration.
[1]
II.
State the plant tissue that transports water from roots to leaves.
[1]
III.
State one adaptation of xylem vessels that reduces resistance to water flow.
[1]
Explain how transpiration generates tension that moves water up xylem.
[3]
Discuss how xylem structure allows water transport under tension without collapse or interruption.
[2]
Question 43
The diagram shows pressure filtration and reuptake across a capillary bed in a mammalian tissue.
I.
Define tissue fluid.
[1]
II.
State why red blood cells and most plasma proteins remain in the capillary during pressure filtration.
[2]
Explain why tissue fluid is released mainly at the arteriole end of a capillary bed and reabsorbed mainly at the venule end.
[3]
Suggest one consequence if reuptake of tissue fluid is reduced for a long period.
[1]
Question 44
The diagrams show circulatory pathways in a bony fish and in a mammal.
I.
State the sequence of organs through which blood passes in the single circulation of a bony fish.
[1]
II.
State the two circuits in the double circulation of a mammal.
[2]
Compare and contrast single and double circulation in terms of pressure and flow to body tissues.
[3]
Discuss one advantage of having separate pulmonary and systemic circuits in mammals.
[2]
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Question 45
The diagram shows the frontal view of a mammalian heart with major blood vessels, chambers and valves visible but not labelled.
I.
State the chamber that receives blood from the vena cava.
[1]
II.
State the artery that receives blood from the left ventricle.
[1]
III.
State the location of the sinoatrial node.
[1]
Explain how valves and the septum help maintain unidirectional flow and separation of blood in the mammalian heart.
[3]
Explain why the left ventricle and coronary vessels are important adaptations for delivering pressurized blood to arteries.
[2]
Question 46
Epidemiological data were collected from several populations to investigate possible risk factors for coronary heart disease.
Population | Saturated fat intake / % of energy | CHD incidence / cases per 100 000 per year | Mean age / years |
|---|---|---|---|
1 | 8 | 45 | 28 |
2 | 10 | 20 | 29 |
3 | 12 | 65 | 31 |
4 | 14 | 50 | 34 |
5 | 16 | 75 | 37 |
6 | 18 | 105 | 41 |
I.
State the function of coronary arteries.
[1]
II.
Outline how an atheroma can lead to occlusion of a coronary artery.
[2]
Explain the consequences of severe occlusion of a coronary artery for heart muscle.
[2]
Evaluate the use of the epidemiological data as evidence that the risk factor causes coronary heart disease.
[3]
Question 47
The graph shows pressure changes in the left atrium, left ventricle and aorta during one cardiac cycle.
I.
State what is meant by systole.
[1]
II.
State how systolic and diastolic blood pressure are identified from an arterial pressure graph.
[2]
Explain how pressure differences cause the opening and closing of valves on the left side of the heart.
[3]
Evaluate the statement that the cardiac cycle is controlled only by pressure changes.
[2]
Question 48
A developing fruit acts as a sink for sucrose produced in mature leaves. Phloem sap moves from leaves to the fruit through sieve tubes.
I.
Define translocation in phloem.
[1]
II.
State one source and one sink in the context described.
[2]
Explain how sieve tube elements and companion cells are adapted for phloem transport.
[3]
Discuss how loading and unloading of sucrose can produce mass flow of phloem sap from source to sink.
[2]
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