plumiRecycling within ecosystems: OCR A‑Level Biology A questions
OCR A-Level Biology A past-paper questions on 6.3.1.3 Recycling within ecosystems, 2016–2025, with mark schemes and examiner’s reports where available.
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Q21(a)
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All 10 questions on Recycling within ecosystems, as a list
- June 2023, Paper 2, Q21(a) (6 marks): Complete the sentences using the most appropriate terms. When animals die microorganisms convert nitrogen-containing molecules in the animals’ bodies to ammonia
- June 2023, Paper 2, Q21(b) (2 marks): Use your knowledge of the nitrogen cycle to suggest and explain why plants do not grow well in soil with a low oxygen content. [2]
- June 2022, Paper 2, Q11 (1 mark): Nitrobacter is a bacterium that is involved in recycling nitrogen in an ecosystem. Which nitrogen cycle reaction is carried out by Nitrobacter? − + O2 → 2NO3 −
- November 2020, Paper 2, Q13 (1 mark): The nitrogen cycle involves a range of reactions and microorganisms. Which of the following processes, A to D, usually requires anaerobic conditions? A conversi
- November 2020, Paper 2, Q14 (1 mark): Which of the following bacteria, A to D, convert ammonium compounds to nitrites? A Azotobacter B Nitrobacter C Nitrosomonas Rhizobium D Your answer [1]
- November 2020, Paper 2, Q20(a)(i) (2 marks): Identify the processes occurring at A and F. A.... ....F... [2]
- November 2020, Paper 2, Q20(a)(ii) (1 mark): The concentration of carbon dioxide (CO_) in the atmosphere varies depending on the time of year. Suggest why the concentration of CO2 in the atmosphere increas
- November 2020, Paper 2, Q20(c) (6 marks): Carbon and nitrogen are elements that are recycled. The flow chart shows the carbon cycle. CO, in the atmosphere E D A H producers consumers dead fossil fuels d
- June 2017, Paper 3, Q4(a) (4 marks): Complete the table to show the locations of each type of bacterium in the cycle and the reactions they perform. Oxidation or Type of Location Reactant(s) Produc
- June 2017, Paper 3, Q4(b)(ii) (2 marks): Leghaemoglobin is a molecule that improves the performance of nitrogenase. It has very similar properties to mammalian haemoglobin. Suggest two ways in which le
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