Respiration: Edexcel International A Level Biology questions

Every Edexcel International A Level Biology exam question on Respiration (specification points 7.1–7.8), 2019–2025, with its mark scheme and examiner’s report.

All 85 questions on Respiration, as a list

June 2025, Unit 5, Q2(a)(i) (1 mark): Name a structure formed by the folding of the inner mitochondrial membrane. (1)
June 2025, Unit 5, Q2(a)(ii) (1 mark): Which is a role of the inner mitochondrial membrane? (1) A to convert glucose to pyruvate B to phosphorylate ADP C to produce glucose from carbon dioxide D to t
June 2025, Unit 5, Q2(b) (3 marks): Describe how reduced NAD is involved in the synthesis of ATP inside a mitochondrion. (3)
June 2025, Unit 5, Q2(c)(i) (1 mark): Which is the role of oxygen molecules in mitochondria? (1) A to accept electrons B to donate electrons C to donate hydrogen ions D to form carbon dioxide
June 2025, Unit 5, Q2(c)(ii) (1 mark): Which part of a mitochondrion contains the electron transport chain (ETC)? (1) A inner mitochondrial membrane B mitochondrial matrix C outer mitochondrial membr
June 2025, Unit 6, Q1(a) (1 mark): Name one artificial hydrogen carrier. (1)
June 2025, Unit 6, Q1(b) (6 marks): Describe an experiment to investigate the rate of respiration of yeast cells at different temperatures, using an artificial hydrogen carrier. (6)
June 2025, Unit 6, Q1(c) (3 marks): Describe how ATP and reduced co‑enzyme are produced in anaerobic respiration. (3)
January 2025, Unit 5, Q7(b)(i) (1 mark): Which describes how ATP is synthesised by chemiosmosis? (1) A hydrogen ions are pumped from the matrix to the intermembrane space through ATP synthase B hydroge
January 2025, Unit 5, Q7(b)(ii) (1 mark): Amytal is a drug that inhibits the electron transport chain in respiration. Which row of the table shows the changes caused by amytal when it is present in a ce
January 2025, Unit 5, Q7(b)(iii) (1 mark): Which molecule is required in the conversion of pyruvate to a 2 carbon compound in the link reaction of respiration? (1) A oxidised NAD B oxidised NADP C reduce
January 2025, Unit 5, Q7(c) (2 marks): Name three products of Krebs cycle. (2)
October 2024, Unit 5, Q3(c)(i) (2 marks): Explain the effect on the lactate concentration from 15 minutes to 60 minutes on the graph. (2)
October 2024, Unit 5, Q3(c)(ii) (1 mark): State one reason why the lactate concentration was measured 15 minutes before starting the exercise. (1)
October 2024, Unit 5, Q3(c)(iii) (1 mark): State one variable that would need to be controlled in this investigation and how this would be achieved. (1)
October 2024, Unit 5, Q5(b)(i) (3 marks): Describe the relationships between mass, resting metabolic rate and pulse rate shown in the table. (3)
June 2024, Unit 5, Q6(a)(i) (1 mark): The diagram shows what happens to the lactate following exercise. Molecule W Molecule Y Lactate Molecule Z Which row shows the molecules in this diagram? (1) Mo
June 2024, Unit 5, Q6(a)(ii) (6 marks): The table and graph show some of the results of this investigation. Lactate concentration in blood / mmol dm–3 Intensity of exercise / a.u. Athlete Non-athlete
June 2024, Unit 5, Q6(b) (4 marks): The photograph shows a coyote. (Source: © Shaun Cunningham/Alamy Stock Photo) Some coyotes have been poisoned with cyanide to prevent them from killing the live
June 2024, Unit 6, Q1(a)(i) (1 mark): State the location in the mitochondria where oxidative phosphorylation takes place. (1)
June 2024, Unit 6, Q1(a)(ii) (1 mark): Name one molecule that carries hydrogen for use in oxidative phosphorylation. (1)
June 2024, Unit 6, Q1(b) (5 marks): Describe an experiment to investigate the effect of temperature on the rate of respiration in yeast, using an artificial hydrogen carrier (redox indicator). (5)
June 2024, Unit 6, Q1(c) (3 marks): Explain why temperature affects the rate of respiration in yeast. (3)
June 2024, Unit 6, Q4(a) (3 marks): Describe preliminary practical work that you might undertake to ensure your proposed method would provide quantitative results. (3)
June 2024, Unit 6, Q4(b) (8 marks): Devise a detailed method, including how you would control and monitor important variables. (8)
June 2024, Unit 6, Q4(d) (3 marks): Suggest three limitations of your proposed method. (3)
January 2024, Unit 5, Q1(a) (1 mark): Which is the correct order of the stages of respiration required for the complete oxidation of glucose? (1) A glycolysis Krebs cycle link reaction B glycolysis
January 2024, Unit 5, Q1(b) (2 marks): Write a balanced equation for the complete oxidation of glucose in aerobic respiration. (2)
January 2024, Unit 5, Q1(c)(i) (1 mark): Which is the respiratory quotient when this lipid is used in aerobic respiration? (1) A 0.67 B 0.71 C 1.06 D 1.42
January 2024, Unit 5, Q1(c)(ii) (2 marks): The complete oxidation of one molecule of this lipid produces 122 molecules of ATP. One molecule of this lipid contains 12 244 kJ of energy. One molecule of ATP
January 2024, Unit 5, Q6(a)(ii) (3 marks): During a sprint race, leg muscles produce lactate. Describe what happens to the lactate at the end of the race. (3)
January 2024, Unit 5, Q8(g) (3 marks): Explain why aerobic exercise increases mitochondrial density and activity (paragraph 9). (3)
October 2023, Unit 6, Q2(b) (2 marks): The graph shows a spirometer trace from one volunteer breathing at rest. 5 4 3 Volume of air / dm3 2 P 1 Q 0 0 20 40 60 80 100 120 140 Time / s The line PQ indi
June 2023, Unit 5, Q2(a)(i) (1 mark): Where is the site of the electron transport chain? (1) A cytoplasm B inner mitochondrial membrane C mitochondrial matrix D outer mitochondrial membrane
June 2023, Unit 5, Q2(a)(ii) (1 mark): Enzymes are involved in the production of ATP by the electron transport chain. Which type of molecule is an enzyme? (1) A carbohydrate B lipid C phospholipid D
June 2023, Unit 5, Q2(a)(iii) (2 marks): Describe the role of reduced NAD in aerobic respiration. (2)
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)
June 2023, Unit 5, Q2(b)(ii) (2 marks): Cyanide stops the transfer of electrons along the electron transport chain. Explain why cyanide does not affect the production of ATP from anaerobic respiration
January 2023, Unit 5, Q5(a) (1 mark): How is water formed during aerobic respiration? (1) A reduction of carbon B reduction of oxygen C phosphorylation of ADP D phosphorylation of glucose
January 2023, Unit 5, Q5(b)(i) (1 mark): The rate of oxygen uptake by the cyclist at 60 minutes was 2.20 dm3 min–1. Which is the rate of carbon dioxide production by the cyclist at 60 minutes? (1) A 1.
January 2023, Unit 5, Q5(b)(ii) (2 marks): The table gives the respiratory quotient for aerobic respiration using fats or carbohydrates as respiratory substrates. Substrate Respiratory quotient Fat 0.7 C
January 2023, Unit 5, Q6(d)(iii) (2 marks): Anaerobic respiration produces lactate. Describe what happens to this lactate. (2)
January 2023, Unit 5, Q8(a) (3 marks): Suggest why there is a relationship between the ageing process and neurodegeneration (paragraphs 1 and 2). (3)
January 2023, Unit 5, Q8(b) (3 marks): Describe how energy released from glucose is used in oxidative phosphorylation (paragraph 2). (3)
January 2023, Unit 5, Q8(c) (3 marks): Explain how free radicals (reactive oxygen species, ROS) can cause damage to mitochondrial DNA (paragraphs 2 and 4). (3)
January 2023, Unit 5, Q8(f) (2 marks): Explain why synaptic mitochondria are more susceptible to ageing than the mitochondria found in other parts of a neurone (paragraph 9). (2)
January 2023, Unit 5, Q8(g) (2 marks): Explain why the mitochondrial genome is essential for oxidative phosphorylation (paragraph 10). (2)
October 2022, Unit 5, Q1(a)(i) (1 mark): How many of these statements about the inner membrane of a mitochondrion are correct? (1) • it is folded (has cristae) • it is the location of ATP synthase • it
October 2022, Unit 5, Q1(a)(ii) (1 mark): Anaerobic respiration produces lactate as a waste product. Which is the result of lactate production? (1) A blood becomes less acidic B muscle becomes less fati
October 2022, Unit 5, Q1(b) (2 marks): Describe how chemiosmosis is involved in the synthesis of ATP. (2)
October 2022, Unit 5, Q1(c) (1 mark): A culture containing respiring cells was supplied with radioactive oxygen molecules. Which will be the first substance to contain radioactive oxygen atoms? (1)
October 2022, Unit 5, Q4(a)(ii) (3 marks): Calculate the volume of oxygen used each hour by a resting elephant with a mass of 4500 kg. Give your answer in standard form. (3) Answer
June 2022, Unit 5, Q7(b)(i) (1 mark): Which is the approximate rate at which carbon dioxide is produced in sample 1? (1) A 3 nmol mg min B 180 nmol mg min C 3 nmol mg–1 min–1 D 180 nmol mg–1 min–1
June 2022, Unit 5, Q7(b)(ii) (4 marks): Explain the results of this investigation. Use the information in the table and your own knowledge of the Krebs cycle to support your answer. (4)
June 2022, Unit 6, Q4(a) (3 marks): Describe preliminary practical work that you might undertake to ensure your proposed method would provide quantitative results. (3)
June 2022, Unit 6, Q4(b) (8 marks): Devise a detailed method, including an explanation of how you would control and monitor important variables. (8)
June 2022, Unit 6, Q4(d) (2 marks): Suggest two limitations of your proposed method. (2)
January 2022, Unit 5, Q1(b) (3 marks): Describe how ATP is synthesised by oxidative phosphorylation in the mitochondrion. (3)
January 2022, Unit 5, Q1(c) (2 marks): Describe how ATP is used to supply energy for biological processes. (2)
January 2022, Unit 5, Q8(f) (4 marks): In the MTT assay, reduced NAD converts an MTT solution from yellow to purple. Describe how the MTT assay could be used to show which of two drugs is more toxic
January 2022, Unit 6, Q4(a) (2 marks): Describe preliminary practical work that you might undertake to ensure your proposed method would provide quantitative results. (2)
January 2022, Unit 6, Q4(b) (8 marks): Devise a detailed method, including how you would control and monitor important variables. (8)
January 2022, Unit 6, Q4(d) (2 marks): Give two limitations of your proposed method. (2)
October 2021, Unit 5, Q5(a)(i) (1 mark): Which row of the table shows the location of each stage? (1) Glycolysis Link reaction Krebs cycle A cytoplasm cytoplasm cytoplasm B cytoplasm mitochondrial matr
October 2021, Unit 5, Q5(a)(ii) (1 mark): A student calculated the volume of oxygen used by a cockroach as 1.7 cm3 hour−1 . The same cockroach produced 1.3 cm3 hour−1 of carbon dioxide in the same time.
October 2021, Unit 5, Q5(a)(iii) (1 mark): Hydramethylnon is an insecticide that is used to treat termite infestations. Hydramethylnon inhibits the electron transport chain. Which row of the table shows
October 2021, Unit 5, Q5(b) (2 marks): The table shows the oxygen consumption and body mass of two animals. Oxygen consumption Body mass Animal / cm3 h−1 / g Southern elephant seal 1.82 × 104 5.00 ×
October 2021, Unit 5, Q5(c) (6 marks): The photograph shows a crocodile (Crocodylus porosus) that lives in saltwater habitats. (Source: © Danny Ye/Shutterstock) An investigation measured the lactate
June 2021, Unit 5, Q1(a) (3 marks): One product of all three stages shown in the table is ATP (adenosine triphosphate). Complete the table to show one other product of each stage. (3) Stage One ot
June 2021, Unit 5, Q1(b) (2 marks): An incomplete equation for the aerobic respiration of a substrate is shown below. Complete the equation by inserting the numbers on the dotted lines to balance
June 2021, Unit 5, Q1(c)(i) (1 mark): Which reaction releases energy from ATP? (1) A the conversion of ADP to ATP B the phosphorylation of ADP C the hydrolysis of ATP D the removal of adenosine mole
June 2021, Unit 5, Q1(c)(ii) (2 marks): Calculate the maximum percentage of energy in a glucose molecule that can be converted to usable energy in ATP. (2) Answer %
June 2021, Unit 5, Q1(c)(iii) (2 marks): Describe what happens to the energy that is not converted to usable energy in a muscle cell. (2)
June 2021, Unit 5, Q1(d) (2 marks): Describe how oxygen is involved in the production of ATP on the cristae in the mitochondria. (2)
January 2021, Unit 5, Q4(b) (6 marks): Inherited mitochondrial diseases affect muscle function. The diagram shows the electron transport chain in a mitochondrion. reduced oxidised TMPD TMPD cytochrom
January 2021, Unit 6, Q2(a)(i) (3 marks): Calculate the mean rate of oxygen uptake in mm3 min–1. The internal diameter of the capillary tube was 0.2 mm. The volume of a cylinder (V) is calculated using
January 2021, Unit 6, Q2(a)(ii) (2 marks): The mean rate of carbon dioxide released by the maggots was 0.11 mm3 min–1. Calculate the respiratory quotient (RQ) value for this investigation. (2) RQ
January 2021, Unit 6, Q2(a)(iii) (1 mark): The soda lime was removed and replaced with glass beads in order to calculate the RQ. Suggest why this allows the student to calculate the RQ. (1)
January 2021, Unit 6, Q2(b)(i) (2 marks): State two biotic variables that could affect this investigation. (2) First variable Second variable
January 2021, Unit 6, Q2(b)(ii) (2 marks): Choose one of the variables you have identified in (b)(i). Describe how this variable could be controlled and the effect it could have on the results if it is n
October 2020, Unit 5, Q1(a)(i) (1 mark): Which of the following describes a step in the process of anaerobic respiration? (1) A decarboxylation of lactate B phosphorylation of hexoses C oxidation of py
October 2020, Unit 5, Q1(a)(ii) (1 mark): What happens to the lactate concentration during a period of anaerobic respiration? (1) A decreases, causing a decrease in blood pH B decreases, causing an incr
October 2020, Unit 5, Q1(b)(i) (1 mark): How do respiratory substrates enter the Krebs cycle? (1) A as molecules containing 2 carbon atoms produced by the link reaction B as molecules containing 3 carb
October 2020, Unit 5, Q1(b)(ii) (2 marks): Draw a diagram of a mitochondrion. Label only the part of the mitochondrion where the Krebs cycle occurs. (2)
October 2020, Unit 5, Q1(b)(iii) (5 marks): Describe the role of chemiosmosis in the synthesis of ATP. (5)

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