plumiThe link reaction, Krebs cycle and coenzymes: OCR A‑Level Biology A questions
OCR A-Level Biology A past-paper questions on 5.2.2.3 The link reaction, Krebs cycle and coenzymes, 2016–2025, with mark schemes and examiner’s reports where available.
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All 12 questions on The link reaction, Krebs cycle and coenzymes, as a list
- June 2025, Paper 1, Q12 (1 mark): What is the function of the link reaction in aerobic respiration? A It converts acetate produced in glycolysis to pyruvate. B It converts pyruvate to oxaloaceta
- June 2025, Paper 1, Q13 (1 mark): Which statement does not describe the Krebs cycle? A It combines an acetyl group with citrate to form oxaloacetate. B It is a source of ATP produced by substrat
- June 2025, Paper 1, Q17(c)(i) (1 mark): State the name of the type of reaction in aerobic respiration that produces CO2. [1]
- June 2025, Paper 1, Q17(c)(ii) (2 marks): State the names of the two stages in respiration where CO2 production occurs. 1 2 [2]
- June 2023, Paper 3, Q2(c)(i) (2 marks): A mitochondrion is shown in Fig. 2.3. Label Fig. 2.3 to show the locations where FAD gains H atoms and where FAD releases H atoms during respiration. • Use the
- June 2023, Paper 3, Q2(c)(ii) (2 marks): The table lists features that are correct for FAD, NAD, both or neither. Complete the table by adding a tick (✓) to a box where the feature is correct and a cro
- November 2021, Paper 1, Q13 (1 mark): NAD, FAD and Coenzyme A (CoA) are molecules that are involved in cellular respiration. Which of the following statements about these molecules is/are correct? 1
- November 2021, Paper 3, Q4(b)(ii) (2 marks): Outline the reactions that must occur to convert α-ketoglutaric acid to oxaloacetate in Fig. 4.2. [2]
- June 2018, Paper 3, Q2(a) (4 marks): Describe the production of ATP by substrate-level phosphorylation in different stages of respiration with reference to the number of ATP molecules produced. [4]
- June 2018, Paper 3, Q2(c)(i) (1 mark): Using the information in Fig. 2, calculate the percentage of carbon atoms in the fatty acid that are able to enter the Krebs cycle. Answer = % [1]
- June 2018, Paper 3, Q2(c)(ii) (1 mark): The percentage of carbon atoms that a reaction makes available for use in the Krebs cycle can be described as the efficiency of the reaction. Calculate the effi
- June 2018, Paper 3, Q2(c)(iii) (1 mark): Fig. 2 shows the role of coenzyme A in beta oxidation. Suggest a role for coenzymes other than coenzyme A in beta oxidation. [1]
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