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GCSE · Biology

B2b The Circulatory System and Heart

AQA 8464 · Calculator allowed · about 90 minutes

Total Marks

Name: _______________________________ Date: ____ / ____ / ______

Answer ALL questions. Show all your working.

Key Facts: The Heart, Blood Vessels and Blood

Original text written for Revision Library.

The heart is a muscular pump with four chambers: two atria (upper) and two ventricles (lower), separated by a septum that stops oxygenated and deoxygenated blood mixing. Blood enters the heart through the vena cava (from the body) and the pulmonary vein (from the lungs), and leaves through the pulmonary artery (to the lungs) and the aorta (to the body). Valves keep blood flowing in one direction only, and the left ventricle has a thicker muscular wall than the right ventricle because it must pump blood at higher pressure around the whole body. Humans have a double circulatory system: blood passes through the heart twice on each full circuit of the body, once around the pulmonary circuit (heart to lungs and back) and once around the systemic circuit (heart to body and back). Cardiac output, the volume of blood pumped by a ventricle each minute, is calculated as heart rate multiplied by stroke volume. Arteries carry blood away from the heart at high pressure, so they have thick, muscular, elastic walls and a narrow lumen. Veins carry blood back to the heart at low pressure, so they have thinner walls, a wider lumen and valves to stop backflow. Capillaries link arteries to veins; their walls are one cell thick, allowing efficient diffusion of oxygen, glucose, carbon dioxide and other substances between blood and body cells. Blood itself is made up of red blood cells (which carry oxygen using haemoglobin), white blood cells (which defend against pathogens), platelets (which help blood clot) and plasma (the liquid that carries dissolved substances). In the lungs, oxygen diffuses into the blood and carbon dioxide diffuses out, across the thin, moist walls of millions of alveoli. Coronary heart disease happens when the coronary arteries, which supply the heart muscle itself, become narrowed by fatty deposits, restricting blood flow to the heart and increasing the risk of a heart attack. Risk is increased by smoking, a diet high in saturated fat, inactivity and excessive alcohol. Treatments include stents (to hold arteries open), statins (to lower blood cholesterol) and, in severe cases, artificial valves or a heart transplant.

The heart has four chambers, each with a specific role in pumping blood around the body.

(a)Which chamber of the heart pumps oxygenated blood to the rest of the body (not including the lungs)?(1)

A) Right atrium
B) Right ventricle
C) Left atrium
D) Left ventricle

(Total for Question 1 is 1 mark)

The heart is a muscular organ that pumps blood around the body.

(a)State the total number of chambers in the human heart.(1)

(b)Name the chamber of the heart that pumps deoxygenated blood to the lungs.(1)

(Total for Question 2 is 2 marks)

Blood vessels carry blood to and from the heart.

(a)Name the blood vessel that carries deoxygenated blood from the body into the right atrium.(1)

(b)Name the blood vessel that carries oxygenated blood away from the left ventricle to the rest of the body.(1)

(c)Name the blood vessel that carries deoxygenated blood from the right ventricle to the lungs.(1)

(d)Name the blood vessel that carries oxygenated blood from the lungs into the left atrium.(1)

(Total for Question 3 is 4 marks)

The heart has several structural features that keep blood flowing correctly and efficiently.

(a)The heart has a septum that separates the left and right sides. Explain why this is important.(2)

(b)Explain the function of the valves found in the heart.(2)

(c)The wall of the left ventricle is thicker and more muscular than the wall of the right ventricle. Explain why.(2)

(Total for Question 4 is 6 marks)

Humans have a double circulatory system.

(a)Describe what is meant by a 'double circulatory system'.(2)

(b)Explain one advantage of a double circulatory system compared with a single circulatory system.(2)

(Total for Question 5 is 4 marks)

Arteries, veins and capillaries have different structures related to their functions.

(a)Give two differences in structure between an artery and a vein.(2)

(b)Explain how the structure of an artery is adapted to carry blood at high pressure away from the heart.(3)

(c)Explain how the structure of a capillary is adapted for the efficient exchange of substances with body tissues.(2)

(Total for Question 6 is 7 marks)

Blood is made up of several different components, each with a specific role.

(a)Name four components of blood.(2)

(b)Describe two adaptations of red blood cells that help them transport oxygen efficiently.(2)

(c)State the function of platelets in the blood.(1)

(d)State the function of white blood cells in the blood.(1)

(Total for Question 7 is 6 marks)

Gas exchange takes place in the lungs, at the surface of millions of tiny air sacs called alveoli.

(a)Name the gas that diffuses from the air in the alveoli into the blood.(1)

(b)Name the gas that diffuses from the blood into the air in the alveoli.(1)

(c)Explain three ways in which alveoli are adapted for efficient gas exchange.(3)

(Total for Question 8 is 5 marks)

A student called Priya carried out a practical investigation into the effect of exercise on pulse rate. She measured her pulse rate before exercise, then performed star jumps continuously for different durations, immediately counting the number of pulse beats felt at her wrist for 15 seconds after each period of exercise. Her results are shown in Table 1.

Table 1

Exercise duration (s)	Beats counted in 15 s	Pulse rate (bpm)
0	18	72
30	23	92
60	27	108
90	30	120
120	34	?

(a)Identify the independent variable in this investigation.(1)

(b)Identify the dependent variable in this investigation.(1)

(c)Give one variable that Priya should control to make this a fair test.(1)

(d)Priya counted 34 beats in 15 seconds after 120 seconds of exercise. Calculate her pulse rate, in beats per minute, to complete Table 1.(2)

(e)Suggest why Priya counted the pulse beats for only 15 seconds, rather than for a full 60 seconds, after each period of exercise.(2)

(f)Describe the pattern shown by the results in Table 1.(2)

(g)Explain, in terms of processes happening in the muscles, why pulse rate increases during exercise.(3)

(h)Suggest one improvement Priya could make to her method to produce more reliable results.(1)

(Total for Question 9 is 13 marks)

Cardiac output is the volume of blood pumped by one ventricle of the heart in one minute. It can be calculated using the equation:
cardiac output = heart rate x stroke volume
(stroke volume is the volume of blood pumped out of a ventricle with each heartbeat)

(a)At rest, a man called Jamal has a heart rate of 72 beats per minute (bpm) and a stroke volume of 70 cm^3. Calculate his cardiac output at rest, in cm³ per minute.(2)

(b)Convert your answer to part (a) into dm³ per minute.(1)

(c)During exercise, Jamal's heart rate increases to 150 bpm and his stroke volume increases to 100 cm^3. Calculate his cardiac output during exercise, in dm³ per minute.(2)

(d)Calculate the percentage increase in Jamal's cardiac output from resting to exercise, using your answers to parts (a) and (c).(3)

(Total for Question 10 is 8 marks)

A student drew a scientific diagram of a red blood cell as seen using a light microscope. The diagram was 28 mm wide. The actual diameter of the red blood cell is 7 micrometres (7 um).

(a)Calculate the magnification of the student's diagram. Use the equation: magnification = image size / actual size.(3)

(b)State why a red blood cell must be viewed using a microscope, rather than with the naked eye.(1)

(Total for Question 11 is 4 marks)

Coronary heart disease (CHD) develops when the coronary arteries become narrowed.

(a)Name the blood vessels that supply the heart muscle itself with oxygen and glucose.(1)

(b)Explain how narrowed coronary arteries can lead to a heart attack.(3)

(c)State one lifestyle risk factor for developing coronary heart disease.(1)

(Total for Question 12 is 5 marks)

Coronary heart disease can be treated using stents or statins.

(a)Describe how a stent works to treat a narrowed coronary artery.(2)

(b)Explain how statins help to reduce the risk of coronary heart disease.(2)

(c)Evaluate one advantage and one disadvantage of treating coronary heart disease with a stent, compared with using statins.(2)

(Total for Question 13 is 6 marks)

A health survey of 2,000 adults found that 400 of them were smokers. Of the 400 smokers, 140 had been diagnosed with coronary heart disease (CHD). Of the remaining 1,600 non-smokers, 128 had been diagnosed with CHD.

(a)Calculate the percentage of smokers in the survey who had been diagnosed with CHD.(2)

(b)Calculate the percentage of non-smokers in the survey who had been diagnosed with CHD.(2)

(Total for Question 14 is 4 marks)

Use your answers to Question 14 to answer the following questions.

(a)Describe the pattern shown by the data in Question 14.(1)

(b)Explain why this survey data alone does not prove that smoking causes coronary heart disease.(2)

(Total for Question 15 is 3 marks)

A national health campaign encourages people to reduce their risk of coronary heart disease (CHD) by taking regular exercise, eating a balanced diet that is low in saturated fat, not smoking, and limiting alcohol consumption.

Discuss how these lifestyle factors are linked to the risk of developing coronary heart disease, and evaluate how effective changing them is likely to be in reducing this risk.

(Total for Question 16 is 6 marks)

Mark scheme · B2b The Circulatory System and Heart

Question 1

(a) B1 D (left ventricle)
(a) Answer: D (left ventricle)

Question 2

(a) B1 4 (four) cao
(a) Answer: 4
(b) B1 right ventricle oe
(b) Answer: Right ventricle

Question 3

(a) B1 vena cava oe
(a) Answer: Vena cava
(b) B1 aorta oe
(b) Answer: Aorta
(c) B1 pulmonary artery oe
(c) Answer: Pulmonary artery
(d) B1 pulmonary vein oe
(d) Answer: Pulmonary vein

Question 4

(a) B1 prevents/stops oxygenated and deoxygenated blood from mixing, oe
(a) B1 so blood pumped to the body has the highest possible concentration of oxygen, allowing efficient aerobic respiration in body cells, oe
(a) Answer: The septum stops oxygenated and deoxygenated blood mixing, so the blood sent to the body carries as much oxygen as possible.
(b) B1 prevent the backflow of blood, oe
(b) B1 ensuring blood only flows in one direction through the heart, maintaining efficient circulation, oe
(b) Answer: Valves stop blood flowing backwards, keeping blood flowing in one direction through the heart.
(c) B1 the left ventricle must pump blood all the way around the whole body (systemic circulation), which requires a greater force/higher pressure than the right ventricle, which only pumps blood to the nearby lungs (pulmonary circulation), oe
(c) B1 a thicker, more muscular wall allows the left ventricle to contract with greater force, generating this higher pressure, oe
(c) Answer: The left ventricle pumps blood around the whole body, which needs a higher pressure than pumping just to the lungs, so it has a thicker, more muscular wall to generate that force.

Question 5

(a) B1 blood passes through the heart twice for each complete circuit of the body, oe
(a) B1 once around the pulmonary circuit (heart to lungs and back) and once around the systemic circuit (heart to the rest of the body and back), oe
(a) Answer: Blood passes through the heart twice on each full circuit: once to the lungs and back (pulmonary circuit), and once to the rest of the body and back (systemic circuit).
(b) B1 blood returning from the lungs passes back through the heart before travelling to the body, so its pressure/speed is boosted between the two circuits, oe
(b) B1 this means oxygenated blood reaches body cells faster and at a higher pressure, allowing more efficient/faster delivery of oxygen for aerobic respiration, oe
(b) Answer: Blood is repressurised by the heart after returning from the lungs, so oxygenated blood reaches the body faster and at higher pressure than in a single circulatory system.

Question 6

(a) B1 an artery has a thicker, more muscular (and elastic) wall than a vein, oe
(a) B1 an artery has a narrower lumen than a vein, and/or veins (but not arteries) contain valves, oe (any one further valid difference)
(a) Answer: An artery has a thicker, more muscular wall and a narrower lumen than a vein; veins also contain valves, which arteries do not.
(b) B1 thick wall containing muscle and elastic fibres, oe
(b) B1 the wall can withstand and stretch/recoil under the high pressure of blood leaving the heart, oe
(b) B1 narrow lumen helps to maintain the high pressure of the blood, oe
(b) Answer: Arteries have thick, muscular, elastic walls that withstand and recoil under high pressure, and a narrow lumen that helps maintain that pressure.
(c) B1 capillary walls are only one cell thick, oe
(c) B1 this gives a short diffusion distance/pathway, allowing oxygen, glucose, carbon dioxide and other substances to diffuse quickly between blood and cells, oe
(c) Answer: Capillary walls are one cell thick, giving a short diffusion distance so substances can be exchanged quickly with body cells.

Question 7

(a) B1 any two of: red blood cells, white blood cells, platelets, plasma
(a) B1 a further two different components from: red blood cells, white blood cells, platelets, plasma (all four different components needed for both marks)
(a) Answer: Red blood cells, white blood cells, platelets and plasma.
(b) B1 biconcave disc shape, giving a large surface area (to volume ratio) for the diffusion of oxygen, oe
(b) B1 no nucleus, leaving more space inside the cell to be packed with haemoglobin, which binds oxygen, oe
(b) Answer: Red blood cells have a biconcave disc shape, increasing surface area for diffusion, and no nucleus, leaving more room for oxygen-carrying haemoglobin.
(c) B1 help the blood to clot at a wound/site of damage, oe
(c) Answer: Platelets help the blood clot at a wound.
(d) B1 defend the body against pathogens/infection, e.g. by engulfing pathogens or producing antibodies, oe
(d) Answer: White blood cells defend the body against pathogens, for example by engulfing them or producing antibodies.

Question 8

(a) B1 oxygen
(a) Answer: Oxygen
(b) B1 carbon dioxide
(b) Answer: Carbon dioxide
(c) B1 a very large total surface area, since there are millions of alveoli, oe
(c) B1 walls that are only one cell thick, giving a short diffusion distance/pathway, oe
(c) B1 a good/dense blood supply (many capillaries), which maintains a steep concentration gradient for diffusion (also accept: a moist lining, allowing gases to dissolve), oe
(c) Answer: Alveoli have a large total surface area, walls only one cell thick, and a dense capillary network, all of which speed up the diffusion of gases.

Question 9

(a) B1 duration of exercise, oe
(a) Answer: Duration of exercise
(b) B1 pulse rate (in beats per minute), oe
(b) Answer: Pulse rate (in beats per minute)
(c) B1 any one of: the same person carries out the test each time / the same type of exercise (star jumps) is used each time / the same rest period is allowed before each repeat / room temperature is kept the same, oe
(c) Answer: E.g. the same type of exercise (star jumps) is used for every repeat.
(d) M1 34 x 4, oe
(d) A1 136 (bpm) cao
(d) Answer: 136 bpm
(e) B1 counting for a shorter time is quicker, so the pulse rate can be measured very soon after exercise stops, before it starts to fall/recover, oe
(e) B1 this also allows the measurement to be repeated more times (to check reliability/calculate a mean), and reduces the chance the pulse rate itself changes noticeably during the counting period, oe
(e) Answer: A 15-second count is quick enough to capture the pulse rate before it starts to recover, and allows repeats to check reliability.
(f) B1 as the duration of exercise increases, pulse rate increases, oe
(f) B1 quotes data to support this, e.g. pulse rate rises from 72 bpm at rest (0 s) to 120 bpm after 90 s of exercise, an increase that is roughly proportional to exercise duration, oe
(f) Answer: Pulse rate increases as exercise duration increases, rising from 72 bpm at rest to 120 bpm after 90 seconds of exercise.
(g) B1 during exercise, muscle cells respire more/faster to release the energy needed for contraction, oe
(g) B1 this increases the muscles' demand for oxygen and glucose, and increases the rate of production of carbon dioxide, oe
(g) B1 the heart beats faster (pulse rate increases) to increase the rate of blood flow (cardiac output), delivering oxygen and glucose to the muscles and removing carbon dioxide more quickly, oe
(g) Answer: Exercising muscles respire faster, needing more oxygen and glucose and producing more carbon dioxide, so the heart beats faster to increase blood flow and meet this demand.
(h) B1 repeat each measurement (at each exercise duration) several times and calculate a mean pulse rate (also accept: use a heart-rate monitor/pulse sensor instead of manually counting beats), oe
(h) Answer: Repeat each measurement several times and calculate a mean pulse rate.

Question 10

(a) M1 72 x 70, oe
(a) A1 5040 cm³/min cao
(a) Answer: 5040 cm³/min
(b) B1 5.04 dm³/min, ft their (a) divided by 1000
(b) Answer: 5.04 dm³/min
(c) M1 150 x 100, oe
(c) A1 15 dm³/min cao (allow 15000 cm³/min)
(c) Answer: 15 dm³/min
(d) M1 increase = their (c) - their (a), in the same units, e.g. 15 - 5.04 = 9.96 dm³/min, ft
(d) dM1 percentage increase = increase / their (a) x 100, oe, dependent on the M1 above
(d) A1 197.6% (accept 198%), awrt
(d) Answer: 197.6% (approximately 198%) increase

Question 11

(a) M1 converts both measurements to the same units, e.g. 28 mm = 28000 um, oe
(a) M1 magnification = 28000 / 7, oe
(a) A1 x4000 (magnification has no units) cao
(a) Answer: x4000
(b) B1 a red blood cell is far too small to be seen/resolved with the naked eye, oe
(b) Answer: It is far too small to be seen with the naked eye.

Question 12

(a) B1 coronary arteries
(a) Answer: Coronary arteries
(b) B1 fatty deposits (plaque/atheroma) build up in the coronary arteries, narrowing them, oe
(b) B1 this restricts/reduces the flow of blood, and so of oxygen and glucose, to the heart muscle, oe
(b) B1 heart muscle cells may respire anaerobically or begin to die from a lack of oxygen, which can trigger a heart attack, oe
(b) Answer: Fatty deposits narrow the coronary arteries, reducing blood flow (and so oxygen and glucose) to the heart muscle; muscle cells can then be starved of oxygen and start to die, causing a heart attack.
(c) B1 any one of: smoking / a diet high in saturated fat / lack of regular exercise / obesity / excessive alcohol consumption / high stress levels, oe
(c) Answer: E.g. smoking.

Question 13

(a) B1 a stent is a small mesh tube that is inserted into the narrowed section of the artery, oe
(a) B1 it is expanded and left in place to hold the artery open, allowing blood to flow through more easily, oe
(a) Answer: A stent is a mesh tube inserted into the narrowed artery and expanded to hold it open, so blood can flow through more easily.
(b) B1 statins reduce the amount of 'bad' (LDL) cholesterol carried in the blood, oe
(b) B1 this slows the rate at which fatty deposits build up in the arteries, reducing the risk of the arteries becoming (further) narrowed, oe
(b) Answer: Statins lower blood cholesterol, which slows the build-up of fatty deposits and so reduces the risk of arteries narrowing further.
(c) B1 advantage, e.g. a stent widens the artery and improves blood flow immediately, whereas statins take time to lower cholesterol and reduce risk, oe
(c) B1 disadvantage, e.g. fitting a stent requires surgery, which carries risks such as infection or bleeding, whereas statins are taken as a tablet and are non-invasive (though they can have side effects and must be taken long-term), oe
(c) Answer: Advantage: a stent has an immediate effect on blood flow, unlike statins which act gradually. Disadvantage: a stent requires invasive surgery with associated risks, whereas statins are non-invasive.

Question 14

(a) M1 140 / 400, oe
(a) A1 35% cao
(a) Answer: 35%
(b) M1 128 / 1600, oe
(b) A1 8% cao
(b) Answer: 8%

Question 15

(a) B1 a much higher percentage of smokers (35%) than non-smokers (8%) in the survey had been diagnosed with CHD, ft their Q14 answers, oe
(a) Answer: A much higher percentage of smokers (35%) than non-smokers (8%) had CHD.
(b) B1 a correlation (link) between two factors does not necessarily mean that one causes the other, oe
(b) B1 there could be other differences (confounding variables) between the smokers and non-smokers in the survey, such as diet, exercise levels, age or family history, that could also explain/contribute to the difference in CHD rates, oe
(b) Answer: Correlation does not prove causation; other confounding factors, such as diet, exercise or family history, could differ between the groups and also explain the difference in CHD rates.

Question 16

Level 3 (5-6): A detailed and coherent scientific account that links at least three lifestyle factors to the biological mechanisms that increase or decrease CHD risk (e.g. cholesterol, arterial damage, blood pressure), together with a well-reasoned evaluation of the effectiveness and limitations of lifestyle changes, logically structured throughout with sustained use of scientific terminology.
Level 2 (3-4): Some scientifically correct description of how one or more lifestyle factors affect CHD risk, with a partial or limited evaluation of how effective changing them would be; ideas are not always well linked.
Level 1 (1-2): Basic, undeveloped statements about lifestyle factors and/or CHD risk, with little or no explanation of the underlying biology and little or no evaluation.
Level 0 (0): No relevant content.
Indicative content:
- A diet high in saturated fat raises the level of 'bad' (LDL) cholesterol in the blood.
- Raised cholesterol increases the rate at which fatty deposits (atheroma/plaque) build up inside the coronary arteries, narrowing them.
- Narrowed coronary arteries restrict blood flow to the heart muscle, increasing the risk of angina or a heart attack.
- Smoking damages the lining of the arteries, making fatty deposits more likely to build up, and carbon monoxide in cigarette smoke reduces the blood's oxygen-carrying capacity.
- Nicotine in cigarettes increases heart rate and blood pressure, increasing the strain on the heart and arteries.
- Lack of exercise and excessive alcohol consumption are linked to obesity and/or raised blood pressure, both of which increase the risk of CHD.
- Regular exercise strengthens the heart muscle, can lower resting heart rate and blood pressure, and helps maintain a healthy body weight, all reducing CHD risk.
- A balanced diet lower in saturated fat helps to keep blood cholesterol levels lower, slowing the build-up of fatty deposits.
- Not smoking prevents further damage to the arteries and allows some risk reduction over time.
- Evaluation: lifestyle changes can be very effective at reducing risk, but only if changes are sustained over the long term; some risk factors, such as age, sex, genetics and family history, cannot be changed by lifestyle alone, so risk cannot be eliminated completely, and medical treatments (e.g. statins, stents) may still be needed alongside lifestyle changes for people already at high risk.

The Circulatory System and Heart - Worksheets, Questions and Revision