Heart, blood vessels and haemoglobin: Edexcel International A Level Biology questions

Every Edexcel International A Level Biology exam question on Heart, blood vessels and haemoglobin (specification points 1.6–1.9), 2019–2025, with its mark scheme and examiner’s report.

All 123 questions on Heart, blood vessels and haemoglobin, as a list

June 2025, AS Unit 1, Q2(a)(i) (1 mark): Which describes this dissociation curve? (1) A linear curve showing a positive correlation B linear curve showing a negative correlation C sigmoid curve showing
June 2025, AS Unit 1, Q2(a)(ii) (1 mark): Which name is given to the effect of increasing carbon dioxide concentration on this dissociation curve? (1) A Benedict B Bohr C Fick D Stahl
June 2025, AS Unit 1, Q2(b) (3 marks): Explain how the structure of haemoglobin is related to its function in transporting oxygen and carbon dioxide. (3)
June 2025, AS Unit 1, Q3(a) (3 marks): The diagram shows part of a cross‑section of an artery. Complete the diagram to show details of the structure of an artery. Label two features of an artery on y
June 2025, AS Unit 1, Q3(b)(i) (1 mark): Which is the ratio of the diameter of the lumen to the thickness of wall in the vena cava? (1) A 0.06 : 1.00 B 1.00 : 0.02 C 1.00 : 16.67 D 60.00 : 1.00
June 2025, AS Unit 1, Q3(b)(ii) (2 marks): Calculate the cross‑sectional area of the lumen of this small vein. Use the formula: cross‑sectional area = πr2 Give your answer as a whole number. (2) Answer µ
June 2025, AS Unit 1, Q4(b) (2 marks): The diagram shows the structure of the heart of a frog. Give one similarity and one difference between the structure of this heart and a mammalian heart. (2) Si
June 2025, AS Unit 1, Q4(c) (6 marks): The diagram shows the distribution of blood flowing through the circulatory system of a frog. The percentages of blood flowing through the parts of the circulat
January 2025, AS Unit 3, Q3(a)(i) (4 marks): Complete the table with the letters of the locations of the four structures listed. (4) Structure Label letter Apex An atrium The place where the right and left
January 2025, AS Unit 3, Q3(a)(ii) (1 mark): Photograph 2 shows the inside of the left side of the heart after it was cut open. (Source: © PjrStudio / Alamy Stock Photo) Photograph 2 Draw a line on photogr
January 2025, AS Unit 3, Q3(a)(iii) (3 marks): Draw a plan of the structures within the rectangle on photograph 2. Label the tendinous cords (heart strings) and the cut surface of the muscular wall of the ve
January 2025, AS Unit 3, Q3(b) (4 marks): The diagram shows a healthy heart and one showing a heart condition called dilated cardiomyopathy (DCM). Healthy heart Heart with DCM Compare and contrast the s
January 2025, AS Unit 3, Q3(c)(ii) (2 marks): When added together, these measurements give the full ventricular circumference. The data is shown in the table. Mean measurement / cm Type of heart 1 2 3 4 Tot
January 2025, AS Unit 3, Q3(c)(iii) (3 marks): The mean circumference of hearts with DCM is larger than the mean circumference of healthy hearts. Discuss the relative effects of the changes in the four indiv
October 2024, AS Unit 1, Q2(a) (1 mark): Blood may contain 5.3 million red blood cells in 1 mm3 of blood. One red blood cell can contain 270 million haemoglobin molecules. Calculate the number of haemo
October 2024, AS Unit 1, Q2(c)(i) (3 marks): Describe the changes in these types of subunits present during each stage of development. (3)
October 2024, AS Unit 1, Q2(c)(ii) (2 marks): The oxygen affinity of fetal haemoglobin is different from adult haemoglobin. Explain why this difference ensures the fetus obtains enough oxygen during develop
October 2024, AS Unit 1, Q4(a)(i) (1 mark): How many times greater is the diameter of the lumen of the aorta than the diameter of the lumen of the capillary? (1) A 17 800 B 17 900 C 178 000 D 179 000
October 2024, AS Unit 1, Q4(a)(ii) (3 marks): Explain why the wall of the aorta is thicker than the wall of a capillary. (3)
October 2024, AS Unit 1, Q4(b) (2 marks): The table shows the durations of ventricular diastole and ventricular systole at two different heart rates. Duration of Duration of Heart rate ventricular diast
October 2024, AS Unit 1, Q4(c) (3 marks): The graph shows the rate of flow of blood through the aorta of a dog with increasing distance from the heart. Rate of ﬂow of 160 blood in a forward direction 14
October 2024, Unit 5, Q8(e) (3 marks): Explain why a ‘falling blood pressure’ might result in poor brain health (Paragraph 20). (3)
June 2024, AS Unit 1, Q4(a)(i) (1 mark): Which pair of blood vessels transports blood to and from the lungs? (1) A P and Q B Q and S C R and P D S and R
June 2024, AS Unit 1, Q4(a)(ii) (1 mark): Which blood vessels have valves along their length? (1) A P B P and R C Q D Q and R
June 2024, AS Unit 1, Q4(a)(iii) (1 mark): Which blood vessel does the coronary artery branch from? (1) A P B Q C R D S
June 2024, AS Unit 1, Q4(c)(ii) (3 marks): Explain why it is important for body cells to be close to capillaries to meet the demands of respiration. Use the information in the question and the table to s
June 2024, AS Unit 1, Q8(a) (3 marks): Describe the structure of a haemoglobin molecule. (3)
June 2024, AS Unit 1, Q8(b) (6 marks): The table shows some information about red blood cells from four species of air- breathing mammals. The species are listed by decreasing size. Oxygen-carrying M
June 2024, AS Unit 1, Q8(c)(i) (2 marks): The decrease in percentage saturation with oxygen of myoglobin from 6 kPa to 4 kPa is 3%. Calculate the difference between this decrease and the decrease for ha
June 2024, AS Unit 1, Q8(c)(ii) (2 marks): Describe the effect of the partial pressure of oxygen on the percentage saturation with oxygen of myoglobin. Use values from the graph to support your answer. (
June 2024, AS Unit 1, Q8(c)(iii) (2 marks): Suggest why the dissociation curve for myoglobin is to the left of the curve for haemoglobin. (2)
June 2024, AS Unit 3, Q2(c) (3 marks): The diagram shows the heart of a fish. atrium sinus venosus bulbus arteriosus blood enters the sinus venosus and ﬂows through to the atrium blood ﬂows from the
June 2024, AS Unit 3, Q2(d) (6 marks): A student suggested that: The larger a fish is, the larger its heart will be. Devise a method that could be used to collect and analyse data to test this sugges
June 2024, Unit 4, Q8(a) (4 marks): Animals, such as seals, that spend much of their time underwater have very large spleens. Spleens store oxygenated red blood cells which are released into the b
January 2024, AS Unit 1, Q1 (5 marks): Red blood cells transport oxygen to the cells of the body. Read through the following description of how oxygen is transported from the lungs to respiring cells
October 2023, AS Unit 1, Q5(a)(i) (1 mark): State what is meant by the term mass transport. (1)
October 2023, AS Unit 1, Q5(a)(ii) (2 marks): All the cells in an animal require glucose. Explain the limitations of diffusion in providing cells with glucose. (2)
October 2023, AS Unit 1, Q5(b) (2 marks): The diagram shows a mammalian heart. Draw arrows on the diagram to show the flow of deoxygenated blood (oxygen‑depleted blood) into, through and out of the hear
October 2023, AS Unit 1, Q5(c) (4 marks): The tunica media is the middle layer in the wall of an artery. The table shows the percentages of some components in the tunica media of arteries of different s
October 2023, AS Unit 1, Q5(d)(i) (1 mark): Which graph shows the diameter of the blood vessels? (1) A graph 1 B graph 3 C graph 4 D graph 6
October 2023, AS Unit 1, Q5(d)(ii) (1 mark): Which graph shows the permeability of the blood vessels? (1) A graph 1 B graph 2 C graph 3 D graph 6
October 2023, Unit 5, Q8(f) (3 marks): Explain how lymph is moved in one direction in the lymphatic system (paragraphs 15 and 16). (3)
October 2023, Unit 5, Q8(g) (3 marks): Suggest how aging may have an adverse effect on the structure of the lymphatic system (paragraph 17). (3)
June 2023, AS Unit 1, Q2(a) (1 mark): Which letter indicates when the atrioventricular (mitral) valves close? (1) A P B Q C R D S
June 2023, AS Unit 1, Q2(b) (1 mark): Calculate the time for one cardiac cycle. (1) Answer seconds
June 2023, AS Unit 1, Q2(c) (3 marks): The volume of blood in the left ventricle changes during the cardiac cycle. Explain these changes. (3)
June 2023, AS Unit 1, Q6(c) (1 mark): Name one organic molecule that contains iron. (1)
June 2023, Unit 5, Q2(b)(i) (3 marks): Carbon monoxide binds to the haem group of haemoglobin. Explain how carbon monoxide will affect the production of ATP. (3)
January 2023, AS Unit 1, Q4(a)(i) (1 mark): How many of the following are correct for blood vessel P? (1) • carries blood to the heart • has valves along its length • has an endothelial lining A 0 B 1 C 2
January 2023, AS Unit 1, Q4(a)(ii) (1 mark): Why is blood vessel Q classified as an artery? (1) A because it carries deoxygenated blood B because it carries oxygenated blood C because it carries blood away
January 2023, AS Unit 1, Q4(a)(iii) (1 mark): Which blood vessel does the coronary artery branch from? (1) A P B Q C R D S
January 2023, AS Unit 1, Q4(a)(iv) (1 mark): When in the cardiac cycle is valve T open? (1) A atrial systole and cardiac diastole B atrial systole only C cardiac diastole and ventricular systole D ventricu
January 2023, AS Unit 1, Q4(b)(i) (1 mark): Calculate the change in mean heart rate for group 2 after 8 days. (1) Answer beats min–1
January 2023, AS Unit 1, Q4(b)(ii) (1 mark): Calculate the mean length of the cardiac cycle for group 2 on day 4. (1) Answer seconds
January 2023, AS Unit 1, Q4(b)(iii) (3 marks): Comment on the conclusions that can be drawn from this investigation. (3)
January 2023, AS Unit 1, Q7(b) (3 marks): Explain why large lungs and a large heart would help a yak to survive at high altitudes. (3)
January 2023, AS Unit 1, Q7(c)(i) (1 mark): The unit given for the volume of a red blood cell is a femtolitre (fl). 1 fl = 1.0 × 10–15 dm3 Give the volume of a red blood cell of a yak in cm3 . Express you
January 2023, AS Unit 1, Q7(c)(iii) (6 marks): Discuss why the blood of yaks enables these animals to live at high altitudes. Use all the information in this question to support your answer. (6)
October 2022, AS Unit 1, Q2(a) (1 mark): What is the name of blood vessel Q? (1) A aorta B pulmonary artery C pulmonary vein D vena cava
October 2022, AS Unit 1, Q2(b)(i) (1 mark): Name the other stage of the cardiac cycle. (1)
October 2022, AS Unit 1, Q2(b)(ii) (2 marks): The duration of ventricular systole is the time it takes for the impulse to pass between E and F, shown on the diagram. Calculate the proportion of time that th
October 2022, AS Unit 1, Q2(c)(i) (1 mark): The distance between B and D is 12.5 mm. Calculate the speed at which the impulse travels between B and D. (1) Answer mm s–1
October 2022, AS Unit 1, Q2(c)(ii) (2 marks): Explain why this speed needs to be slower than the speeds that the impulse travels between other parts of the heart. (2)
October 2022, AS Unit 1, Q3(a) (2 marks): Describe how the structure of capillaries relates to their function. (2)
October 2022, AS Unit 1, Q3(b) (3 marks): Draw a cross‑section of an artery to show details of its structure. Label two features of the artery on your diagram. (3)
October 2022, AS Unit 1, Q3(c) (2 marks): Explain why veins need valves along their length. (2)
October 2022, AS Unit 1, Q3(d) (3 marks): Deoxygenated blood is taken to the lungs and oxygenated blood is taken away from the lungs. Complete the graph to show the changes in partial pressure of oxygen
June 2022, AS Unit 1, Q4(a) (3 marks): Complete the table. Use the formula: surface area = 2πrl where r is the radius of the blood vessel and l is the length of the vessel. (3)
June 2022, AS Unit 1, Q4(b) (3 marks): Explain why the velocity of blood flow in the large arteries is slower than the velocity of blood flow in the aorta. (3)
June 2022, AS Unit 1, Q4(c) (2 marks): Explain why the total surface area of the capillaries needs to be so high. (2)
June 2022, AS Unit 1, Q4(d)(i) (1 mark): The diagrams show the relative proportions of components found in blood vessel walls. Which diagram represents the wall of a large artery? (1) A Key: B endothel
June 2022, AS Unit 1, Q4(d)(ii) (1 mark): Draw a diagram, using the style above, to represent the wall of a capillary. (1)
January 2022, AS Unit 1, Q2(a)(i) (1 mark): What is the name of the blood vessel labelled G? (1) A aorta B pulmonary artery C pulmonary vein D vena cava
January 2022, AS Unit 1, Q2(a)(ii) (1 mark): Which row of the table identifies the stages before and after stage F? (1) Stage before stage F Stage after stage F A atrial systole cardiac diastole B atrial s
January 2022, AS Unit 1, Q2(b)(i) (2 marks): Calculate the heart rate of this person. Express your answer to 3 significant figures. (2) Answer beats min–1
January 2022, AS Unit 1, Q2(b)(ii) (3 marks): Another line could be drawn on this graph to show the pressure changes in the right ventricle. Describe the shape and position of this line. Give reasons for yo
January 2022, AS Unit 1, Q5(a)(ii) (2 marks): Explain the role of collagen in the wall of the aorta. (2)
January 2022, AS Unit 1, Q5(b) (6 marks): Age and sex affect the types and density of collagen found in the wall of the aorta. These are thought to cause aortic stiffness. In one study, scientists inves
January 2022, AS Unit 1, Q8(c)(i) (2 marks): A p50 value is the partial pressure of oxygen that results in 50% saturation of haemoglobin. Calculate the largest difference in the p50 values between a person
January 2022, AS Unit 1, Q8(c)(ii) (2 marks): Identify two conclusions, other than the difference in p50 values, that can be made from this graph. (2) Conclusion 1 Conclusion 2
January 2022, AS Unit 1, Q8(c)(iv) (3 marks): Sickle cell disease can result in death. Explain why the changes in the structure of haemoglobin and the shape of the red blood cells could result in death in a
October 2021, AS Unit 1, Q3(a) (3 marks): The diagram shows the structure of a human heart. Label the diagram with the names of the four major blood vessels. (3)
October 2021, AS Unit 1, Q3(b) (3 marks): The table shows some structures and the types of blood vessel that they are found in. Put a cross in each row to show where these structures are found. (3) Foun
October 2021, AS Unit 1, Q3(c) (3 marks): The graph shows the velocity of the blood as it flows through the arteries into the capillaries and then into the veins. vein artery arterioles venules capillar
October 2021, AS Unit 1, Q4(b)(ii) (2 marks): Explain why the circulation of a butterfly is different from the circulation of a mammal. (2)
January 2021, AS Unit 1, Q2(a) (2 marks): Five litres of blood can pass through a human heart each minute. Calculate the volume of blood that passes through this heart in 24 hours. Give your answer in s
January 2021, AS Unit 1, Q2(b) (2 marks): Blood leaves the heart through the arteries. Compare and contrast the structure of the aorta with the structure of the pulmonary artery. (2)
January 2021, AS Unit 1, Q2(c) (3 marks): Blood returns to the heart through the veins. The diagram shows the outline of a vein. The direction of flow of blood is also shown. Complete and label the diag
January 2021, AS Unit 1, Q4(a)(i) (1 mark): State the role of the structure labelled P. (1)
January 2021, AS Unit 1, Q4(b)(i) (2 marks): Explain why the oxygen dissociation curve of adult haemoglobin is different from that of fetal haemoglobin. (2)
January 2021, AS Unit 3, Q3(a)(i) (2 marks): Name the structures A, B, C and D shown in the diagram. (2) A B C D
January 2021, AS Unit 3, Q3(a)(ii) (3 marks): The photograph shows a heart after it has been dissected. (Source: © PjrStudio / Alamy Stock Photo) Draw a plan of the structures within the rectangle shown on
January 2021, AS Unit 3, Q3(a)(iii) (2 marks): State the function of the two structures labelled on your drawing. (2) Label Function . Label Function .
January 2021, AS Unit 3, Q3(b)(i) (2 marks): Calculate the percentage increase in thickness of the muscle in the HC heart compared with the normal heart, using the lines labelled M. Give your answer to two
January 2021, AS Unit 3, Q3(b)(ii) (4 marks): Compare and contrast these two hearts. (4)
January 2021, AS Unit 3, Q3(b)(iii) (3 marks): Athletes can also develop cardiac hypertrophy as a result of exercise programmes (ECH). Individuals with HC and individuals with ECH show changes in the thickne
January 2021, AS Unit 3, Q3(b)(iv) (4 marks): Determine the effects of ECH and HC on artery thickness. (4)
October 2020, AS Unit 1, Q3(a)(i) (1 mark): Which row of the table describes the atria and ventricles during atrial systole? (1) Atria Ventricles A contracted contracted B contracted relaxed C relaxed con
October 2020, AS Unit 1, Q3(a)(ii) (2 marks): Explain why there is a delay of 0.01 seconds between atrial systole and ventricular systole. (2)
October 2020, AS Unit 1, Q3(a)(iii) (2 marks): Using the information in the diagram, calculate the duration of ventricular systole in milliseconds. Express your answer in standard form. (2) Answer ms
October 2020, AS Unit 1, Q3(a)(iv) (1 mark): State what proportion of the cardiac cycle is spent in ventricular diastole. (1)
October 2020, AS Unit 1, Q3(b) (3 marks): A typical cardiac cycle takes 0.86 seconds. During exercise, the heart rate increases and the duration of the cardiac cycle decreases. Calculate the increase in
January 2020, AS Unit 1, Q2(a) (1 mark): Which diagram shows the direction of blood flow through the vena cava? (1) A C B D
January 2020, AS Unit 1, Q2(b) (1 mark): Which row in the table describes the blood flow through the pulmonary artery and the pulmonary vein? (1) Blood flow through pulmonary artery Blood flow through
January 2020, AS Unit 1, Q2(c) (3 marks): The table describes the atrioventricular (AV) valves and the semilunar (SL) valves during the cardiac cycle. Which description is true for each stage of the car
January 2020, AS Unit 1, Q2(d) (2 marks): Describe how the events of the cardiac cycle change when the demand of body cells for oxygen increases. (2)
January 2020, AS Unit 1, Q7(a)(i) (1 mark): State what is meant by the term partial pressure. (1)
January 2020, AS Unit 1, Q7(a)(ii) (3 marks): Explain how the structure of haemoglobin causes the oxygen dissociation curve of haemoglobin to be this sigmoidal (S) shape. (3)
January 2020, AS Unit 1, Q7(b)(i) (1 mark): Suggest why the partial pressure of oxygen in the air in the alveoli is lower than in the atmosphere. (1)
January 2020, AS Unit 1, Q7(b)(ii) (3 marks): Explain why the partial pressure of oxygen decreases as the blood flows through the arteries and into the veins. (3)
January 2020, AS Unit 1, Q7(b)(iii) (1 mark): Determine the percentage saturation of haemoglobin in the blood as it leaves the lungs of the person at high altitude. Use the point marked X on the graph and t
January 2020, AS Unit 1, Q7(b)(iv) (4 marks): Explain why the percentage saturation of haemoglobin in a person at high altitude is much lower than in a person at sea level. (4)
June 2019, AS Unit 1, Q7(a) (1 mark): Estimate the length of the neck of this giraffe from the shoulders, using the information in the photograph. (1) Answer m
June 2019, AS Unit 1, Q7(b) (2 marks): The heart of an adult giraffe can be 60 cm long. Explain why the heart of a giraffe needs to be so large. (2)
June 2019, AS Unit 1, Q7(c)(i) (3 marks): Draw a labelled diagram of an artery, as seen in section. (3)
June 2019, AS Unit 1, Q7(c)(ii) (2 marks): Explain why the arteries near the heart of a giraffe are highly elastic. (2)
June 2019, AS Unit 1, Q7(d)(i) (2 marks): Explain why very narrow capillaries prevent excessive bleeding. (2)
June 2019, AS Unit 1, Q7(d)(ii) (2 marks): The red blood cells of the giraffe are about one third the size of human red blood cells, so that they can pass through the very narrow capillaries. The small s
January 2019, AS Unit 1, Q4(a) (3 marks): Explain why it is important that blood vessel X branches directly from the aorta. (3)
January 2019, AS Unit 1, Q4(b)(i) (2 marks): Explain which stage of the cardiac cycle is shown in this diagram. (2)
January 2019, AS Unit 1, Q4(b)(ii) (3 marks): Draw arrows on the diagram to show the flow of blood through the left side of the heart and into the aorta. (3)
January 2019, AS Unit 1, Q4(c) (3 marks): The graph shows the changes in the internal diameter of the aorta during two cardiac cycles. 14 Internal diameter of 13 aorta / mm 12 Time Explain the changes i
January 2019, AS Unit 1, Q8(c) (6 marks): Graph 1 shows the oxygen dissociation curve of haemoglobin for a mouse and for an elephant. Graph 1 elephant 100 mouse 80 Percentage 60 saturation of haemoglobi

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