References only, not question text. Open Official paper ↗ where Cambridge publishes the paper,
or see the official Cambridge past-papers page; for other papers, ask your
school. “Paper 42” means Paper 4, variant 2.
Practice questions
Original questions written by HomiLabs in the style of the exam, with answers and mark schemes. They are not
Cambridge past paper questions and have not been reviewed by Cambridge. Try each one before opening the answer.
Q1Circulatory systems & the heart · Core · Paper 4 style · 3 marks
(a)A fish has a single circulation and a mammal has a double circulation. Explain the difference between these two systems.[2]
(b)State one advantage of a double circulation.[1]
Show answer
(a) Single: blood passes through the heart once for each complete circuit of the body (heart → gills → body → heart). Double: blood passes through the heart twice for each circuit (once to the lungs, once to the rest of the body).
B1 single = once through heart per circuit; B1 double = twice (pulmonary and systemic circuits).
(b) Blood can be pumped to the body at a higher pressure (after returning from the lungs), so oxygenated blood reaches tissues faster.
B1; accept keeps oxygenated and deoxygenated blood separate.
Q2Circulatory systems & the heart · Core · Paper 4 style · 4 marks
(a)Put these structures in the order in which a red blood cell passes through them, starting at the vena cava:left atrium, aorta, right ventricle, lungs, pulmonary vein, right atrium, left ventricle, pulmonary artery[3]
(b)State where in this pathway the blood becomes oxygenated.[1]
Show answer
(a) vena cava → right atrium → right ventricle → pulmonary artery → lungs → pulmonary vein → left atrium → left ventricle → aorta
B3 all correct; B2 one structure out of place; B1 the right side (RA → RV → pulmonary artery) or the left side correct.
(b) In the lungs (capillaries around the alveoli).
B1.
Q3Circulatory systems & the heart · Core · Paper 2 style · 1 mark
(a)Which blood vessel carries oxygenated blood into the left atrium?[1]
Show answer
(a) C pulmonary vein
The pulmonary vein brings oxygenated blood from the lungs to the left atrium. The pulmonary artery carries deoxygenated blood away from the heart to the lungs.
Q4Circulatory systems & the heart · Core · Paper 6 style · 3 marks
A doctor at a clinic in Hyderabad wants to check the heart of a patient.
(a)State three ways in which the activity of the heart can be monitored.[3]
Show answer
(a) Measuring pulse rate (at wrist or neck); listening to the sounds of the valves closing with a stethoscope; electrocardiogram (ECG).
1 mark each.
Q5Circulatory systems & the heart · Core · Paper 4 style · 4 marks
(a)Name the part of the heart described by each statement.(i) the chamber that pumps blood to the lungs(ii) the chamber that receives blood from the vena cava(iii) the wall of muscle that separates the left and right sides(iv) the chamber with the thickest wall[4]
Show answer
(a) (i) right ventricle; (ii) right atrium; (iii) septum; (iv) left ventricle
B1 each.
Q6Circulatory systems & the heart · Standard · Paper 4 style · 3 marks
(a)Explain why the wall of the left ventricle is thicker than the wall of the right ventricle.[2]
(b)State the function of the septum.[1]
Show answer
(a) The left ventricle pumps blood all round the body, which needs a higher pressure; the right ventricle only pumps blood to the nearby lungs (low pressure protects lung capillaries). Thicker wall = more muscle = stronger contraction.
B1 left pumps to whole body / further; B1 needs higher pressure / more muscle for stronger contraction.
(b) Separates oxygenated blood (left side) from deoxygenated blood (right side), so they do not mix.
B1.
Q7Circulatory systems & the heart · Standard · Paper 4 style · 4 marks
(a)Name the valves between the atria and the ventricles and state their function.[2]
(b)Explain how the semilunar valves at the base of the aorta and pulmonary artery help the heart to work efficiently.[2]
Show answer
(a) Atrioventricular valves (bicuspid on the left, tricuspid on the right); they prevent blood flowing back into the atria when the ventricles contract.
B1 name; B1 prevent backflow into the atria.
(b) They close when the ventricles relax, so blood in the arteries cannot flow back into the ventricles; this keeps blood moving in one direction.
B1 close when ventricles relax / pressure in artery higher; B1 prevent backflow into ventricles / one-way flow.
Q8Circulatory systems & the heart · Standard · Paper 6 style · 6 marks
Five students at a school in Rawalpindi measure their pulse rate at rest and immediately after two minutes of skipping.Student : resting / beats per min : after exercise / beats per min1 : 72 : 1282 : 68 : 1203 : 75 : 1344 : 70 : 1265 : 65 : 117
(a)Calculate the mean resting pulse rate and the mean pulse rate after exercise.[2]
(b)Calculate the percentage increase in mean pulse rate. Give your answer to the nearest whole number.[2]
(c)Suggest two variables that should be controlled.[2]
Show answer
(a) Resting 70 beats/min; after exercise 125 beats/min
B1 each.
(b) 79 %
(125 − 70) ÷ 70 × 100 (M1) = 78.6 → 79 % (A1).
(c) Any two of: type of exercise; duration / intensity of exercise; time the pulse is counted for; time after exercise when pulse is measured; resting time before the first reading.
1 mark each.
Q9Circulatory systems & the heart · Standard · Paper 4 style · 4 marks
(a)Explain why the heart rate increases during a game of football.[3]
(b)Name the hormone that increases heart rate before the match begins.[1]
Show answer
(a) Muscles respire faster and need more oxygen and glucose; faster heart rate delivers more blood (oxygen, glucose) to muscles; and removes more carbon dioxide (and heat) from them.
B1 more respiration in muscles / more energy needed; B1 more oxygen and glucose delivered; B1 more carbon dioxide removed.
(b) Adrenaline.
B1.
Q10Circulatory systems & the heart · Standard · Paper 2 style · 1 mark
(a)Which row describes the valves while the ventricles are contracting and pumping blood out of the heart?[1]
Show answer
(a) C atrioventricular valves closed; semilunar valves open
As the ventricles contract the atrioventricular valves close to stop backflow into the atria, and the semilunar valves are pushed open so blood leaves through the arteries. B gives the opposite.
Q11Circulatory systems & the heart · Standard · Paper 2 style · 1 mark
(a)Which sequence shows the path of blood in the circulation of a fish?[1]
Show answer
(a) A heart → gills → body → heart
A fish has a single circulation: blood goes from the heart to the gills, then directly to the body and back to the heart. C and D describe a double circulation.
Q12Circulatory systems & the heart · Challenge · Paper 6 style · 6 marks
A student counts her pulse for 15 seconds at one-minute intervals after running. Her resting rate is 72 beats per minute.Time after running / min : beats in 15 s0 : 311 : 272 : 243 : 214 : 305 : 186 : 18
(a)Convert each count into a pulse rate in beats per minute.[2]
(b)Identify the anomalous result and suggest one reason for it.[2]
(c)Using the results, state how long it took for the pulse rate to return to its resting value (72 beats/min).[1]
(d)Explain why counting for 15 seconds and multiplying by 4 is less accurate than counting for a full minute.[1]
Multiply each 15-second count by 4 (M1); all correct (A1).
(b) 4 minutes (120 beats/min); e.g. the student miscounted / moved or talked / lost the pulse / counted for longer than 15 s.
B1 4 min reading; B1 plausible reason.
(c) 5 minutes.
B1.
(d) Any counting error is multiplied by 4 (a miss of one beat gives an error of 4 beats/min).
B1.
Q13Circulatory systems & the heart · Challenge · Paper 4 style · 5 marks
Cardiac output is the volume of blood pumped by one ventricle per minute.cardiac output = heart rate × stroke volumeA trained athlete from Karachi has a resting heart rate of 52 beats/min and a stroke volume of 96 cm³. A student who does not train has a resting heart rate of 75 beats/min and a stroke volume of 66 cm³.
(a)Calculate the cardiac output of each person in dm³ per minute. Give your answers to 3 significant figures.[3]
(b)Suggest why the athlete has a lower resting heart rate but almost the same cardiac output.[2]
Show answer
(a) Athlete: 4.99 dm³/min; other student: 4.95 dm³/min
(b) Training has made the heart muscle stronger / larger, so each beat pumps more blood (larger stroke volume); fewer beats are needed to deliver the same volume of blood.
Q14Circulatory systems & the heart · Challenge · Paper 4 style · 4 marks
Some babies are born with a hole in the septum between the left and right ventricles. In some of these babies, deoxygenated blood passes through the hole from the right ventricle into the left ventricle.
(a)Explain how this affects the oxygen concentration of the blood in the aorta.[2]
(b)Suggest two symptoms a baby with this condition might show.[2]
Show answer
(a) Deoxygenated blood from the right ventricle mixes with oxygenated blood in the left ventricle; so blood in the aorta has a lower oxygen concentration than normal.
B1 mixing of oxygenated and deoxygenated blood; B1 lower oxygen in aorta / to body.
(b) Any two of: tiredness / lack of energy; breathlessness; slow growth / poor feeding; bluish skin or lips.
1 mark each, linked to less oxygen reaching tissues.
Q15Circulatory systems & the heart · Challenge · Paper 4 style · 5 marks
The table shows the pressure in the left ventricle and in the aorta during one heartbeat.Time / s : left ventricle / kPa : aorta / kPa0.0 : 1 : 110.1 : 8 : 100.2 : 16 : 150.3 : 15 : 14.50.4 : 9 : 130.5 : 2 : 120.6 : 1 : 11.5
(a)Using the table, state the times at which the semilunar valve in the aorta is open. Explain how you decided.[2]
(b)Calculate the difference between the maximum and minimum pressure in the aorta.[1]
(c)Explain why the pressure in the aorta never falls as low as the pressure in the left ventricle.[2]
Show answer
(a) 0.2 s and 0.3 s; this is when the pressure in the left ventricle is higher than the pressure in the aorta.
B1 both times; B1 ventricle pressure greater than aortic pressure.
(b) 5 kPa
15 − 10 = 5 kPa (B1).
(c) The semilunar valve closes so blood cannot flow back into the ventricle; the elastic wall of the aorta recoils, keeping pressure up between beats.
Q16Circulatory systems & the heart · Challenge · Paper 5 style · 6 marks
(a)Plan an investigation to find out how the length of time spent exercising affects a person's heart rate. Include what you would measure, how you would make it a fair test, how you would record the results and how you would reach a conclusion.[6]
Show answer
(a) Measure resting pulse; do the same exercise (e.g. step-ups at a fixed rate) for 1, 2, 3, 4, 5 minutes; measure pulse immediately afterwards for 1 minute; rest until pulse returns to resting before the next trial; repeat and calculate means; plot pulse against time.
1 mark each, max 6: measure resting pulse first; independent variable – exercise times (at least 4 values); same type and intensity of exercise (e.g. step height and rate set by a metronome); measure pulse at wrist/neck for 60 s (or with a pulse monitor) immediately after; rest until pulse returns to resting rate between trials; same person / same conditions (same time of day, no food or drink); repeat each time and calculate a mean; table: exercise time / min against pulse rate / beats per min; conclusion from graph trend; safety: stop if dizzy.
Q17Blood vessels · Core · Paper 4 style · 3 marks
(a)Compare arteries, veins and capillaries by stating for each: the relative thickness of the wall, the size of the lumen, and whether valves are present.[3]
Show answer
(a) Arteries: thick muscular elastic wall, narrow lumen, no valves (except at base of aorta/pulmonary artery). Veins: thin wall, wide (large) lumen, valves present. Capillaries: wall one cell thick, very narrow lumen, no valves.
B1 per vessel with all three features correct.
Q18Blood vessels · Core · Paper 2 style · 1 mark
(a)Which blood vessel carries blood from the small intestine to the liver?[1]
Show answer
(a) B hepatic portal vein
The hepatic portal vein carries blood rich in absorbed food from the gut to the liver. The hepatic vein carries blood away from the liver.
Q19Blood vessels · Standard · Paper 4 style · 5 marks
(a)Explain how the structure of a capillary is related to its function.[2]
(b)Explain how the structure of an artery is related to its function.[2]
(c)Explain why veins have valves.[1]
Show answer
(a) Wall is one cell thick so diffusion distance is short; substances (oxygen, glucose) diffuse quickly into tissues / narrow lumen brings red cells close to tissue cells.
B1 thin wall / one cell thick; B1 short diffusion distance / exchange of materials.
(b) Thick muscular and elastic wall withstands high pressure from the heart; elastic tissue stretches and recoils to maintain pressure / smooth flow.
B1 thick wall withstands high pressure; B1 elastic recoil.
(c) Blood in veins is at low pressure; valves prevent backflow (keep blood moving towards the heart).
B1.
Q20Blood vessels · Standard · Paper 4 style · 4 marks
(a)Name the blood vessel that:(i) carries blood to a kidney(ii) carries blood away from the liver(iii) carries deoxygenated blood from the heart to the lungs(iv) carries oxygenated blood from the heart to the body[4]
Q21Blood vessels · Challenge · Paper 4 style · 5 marks
The mean blood pressure was measured in different vessels of a person at rest.Vessel : mean pressure / kPaaorta : 13large arteries : 12arterioles : 7capillaries : 3large veins : 1
(a)Calculate the percentage fall in pressure between the aorta and the capillaries. Give your answer to the nearest whole number.[2]
(b)Blood pressure in large veins is very low. Explain how blood in the leg veins is still returned to the heart.[3]
Show answer
(a) 77 %
(13 − 3) ÷ 13 × 100 (M1) = 76.9 → 77 % (A1).
(b) Valves in veins prevent backflow; contraction of skeletal muscles around the veins squeezes them and pushes blood towards the heart; wide lumen gives little resistance to flow.
Q22Blood vessels · Challenge · Paper 6 style · 5 marks
Rings of the same width were cut from an artery and a vein from a goat (from a butcher). Each ring was hung from a hook, its length measured, a 50 g mass hung on it, and the length measured again. The mass was then removed.Ring : length at start / mm : length with mass / mm : length after mass removed / mmartery : 20 : 26 : 20.5vein : 20 : 33 : 30
(a)Calculate the percentage increase in length of each ring when the mass was added.[2]
(b)Using the results, compare the elasticity of the two rings and explain why this property of the artery wall is useful.[2]
(c)Suggest one way to make this investigation more reliable.[1]
(b) The artery ring stretched less and returned almost to its original length (20.5 mm), so its wall is elastic; the vein ring stayed stretched (30 mm), so it is much less elastic. Elastic recoil of the artery wall helps keep blood pressure up and blood flowing smoothly between heartbeats.
B1 artery recoils almost fully / more elastic than vein, with data; B1 recoil maintains pressure / evens out flow.
(c) Repeat with several rings from each vessel (from more animals) and calculate means.
B1.
Q23Blood components & clotting · Core · Paper 4 style · 6 marks
(a)State the function of each of the following blood components: (i) red blood cells, (ii) phagocytes, (iii) lymphocytes, (iv) platelets.[4]
(b)Name two substances transported dissolved in plasma.[2]
Show answer
(a) (i) transport oxygen (using haemoglobin); (ii) engulf and digest pathogens (phagocytosis); (iii) produce antibodies; (iv) help blood to clot.
B1 each.
(b) Any two of: glucose, amino acids, carbon dioxide, urea, hormones, ions (salts), water, plasma proteins.
1 mark each.
Q24Blood components & clotting · Core · Paper 2 style · 1 mark
(a)Which part of the blood carries carbon dioxide, urea and hormones?[1]
Show answer
(a) A plasma
These substances are carried dissolved in the plasma. Red blood cells mainly carry oxygen.
Q25Blood components & clotting · Standard · Paper 4 style · 5 marks
A boy cuts his knee while playing cricket.
(a)Describe what happens in the blood to form a clot when the skin is cut.[3]
(b)State two benefits of blood clotting.[2]
Show answer
(a) Platelets are involved; soluble fibrinogen is converted to insoluble fibrin; fibrin forms a mesh of fibres that traps red blood cells, forming a clot.
(b) Prevents loss of blood; prevents entry of pathogens.
B1 each.
Q26Blood components & clotting · Standard · Paper 6 style · 4 marks
Red blood cell counts were measured for two healthy adults of the same age.Person living in Karachi (sea level): 5.0 million per mm³Person living in Murree (about 2300 m above sea level): 5.9 million per mm³
(a)Calculate the percentage difference in red blood cell count of the person living in Murree compared with the person living in Karachi.[2]
(b)Suggest an explanation for the difference.[2]
Show answer
(a) 18 % higher
(5.9 − 5.0) ÷ 5.0 × 100 (M1) = 18 % (A1).
(b) Air at high altitude contains less oxygen (lower pressure); more red blood cells / haemoglobin carry more oxygen to the tissues.
B1 less oxygen at altitude; B1 more red cells increase oxygen transport.
Q27Blood components & clotting · Challenge · Paper 4 style · 6 marks
In a blood smear, 200 white blood cells were counted: 136 phagocytes, 56 lymphocytes and 8 other white cells.
(a)Calculate the percentage of white blood cells that were lymphocytes.[1]
(b)Describe how a phagocyte and a lymphocyte can be distinguished when seen under a microscope.[2]
(c)A week later the person develops a bacterial infection. Suggest how the numbers of each type of white blood cell change and explain why.[3]
Show answer
(a) 28 %
56 ÷ 200 × 100 = 28 % (B1).
(b) Phagocyte: lobed (multi-lobed) nucleus and granular cytoplasm; lymphocyte: large round nucleus filling most of the cell, little cytoplasm.
B1 each.
(c) Both increase; more phagocytes to engulf and digest the bacteria; more lymphocytes to make antibodies against the bacterial antigens.
B1 increase; B1 phagocytes engulf/digest; B1 lymphocytes produce (specific) antibodies.
Q28Blood components & clotting · Challenge · Paper 4 style · 4 marks
Dengue fever is common in Pakistan after the monsoon. In one patient the platelet count fell from 250 000 per mm³ to 40 000 per mm³.
(a)Calculate the percentage fall in platelet count.[2]
(b)Explain why doctors watch for bleeding and bruising in this patient.[2]
(b) Platelets are needed for blood clotting; with fewer platelets, blood clots slowly / less well, so small damaged vessels keep bleeding.
B1 platelets needed for clotting; B1 so clotting is slower and bleeding continues.
Q29Coronary heart disease · Standard · Paper 4 style · 6 marks
(a)State the function of the coronary arteries.[1]
(b)Explain how a blockage in a coronary artery can cause a heart attack.[3]
(c)State two risk factors for coronary heart disease that a person can change.[2]
Show answer
(a) Supply the heart muscle with oxygenated blood (oxygen and glucose).
B1.
(b) Fatty deposits (cholesterol) build up in the artery wall and narrow it / a clot forms; less blood, oxygen and glucose reach part of the heart muscle; that muscle cannot respire aerobically, so it stops contracting / dies.
B1 fatty deposit / clot blocks artery; B1 less oxygen (and glucose) to heart muscle; B1 less respiration / muscle cells die / cannot contract.
(c) Any two of: diet high in saturated fat / salt; smoking; lack of exercise; stress; obesity.
1 mark each; not age, sex or genes.
Q30Coronary heart disease · Challenge · Paper 4 style · 5 marks
A study followed men aged 45–60 for ten years.Group : deaths from coronary heart disease per 100 000 men per yearnon-smokers : 120smoke 1–14 cigarettes per day : 210smoke 15 or more cigarettes per day : 390
(a)Calculate how many times greater the death rate is for heavy smokers than for non-smokers.[1]
(b)Describe what the data show about smoking and coronary heart disease.[2]
(c)Explain why these data alone do not prove that smoking causes coronary heart disease.[2]
Show answer
(a) 3.25 times
390 ÷ 120 = 3.25 (B1).
(b) Death rate increases as the number of cigarettes smoked increases; heavy smokers have over three times the death rate of non-smokers.
B1 positive correlation; B1 quoting figures.
(c) Other factors could be involved (diet, exercise, age, stress, genes); smokers may differ from non-smokers in these ways; correlation does not show cause.
B1 other risk factors not controlled; B1 correlation ≠ causation.
Similar questions
Questions that test the same subtopic in different years, grouped so you can work on one skill at a time.
References only: find each question in its paper (official link where available, otherwise through your school).
Circulatory systems & the heartBanker62 questions · 9/9 sessions
