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9 marksEnergy Flow and Nutrient Cycling

CAPE Biology Unit 2 · May/June 2024 · Paper 2 · Question 1(c)

Tropical rainforests contribute about 70% of terrestrial nitrogen fixation. They produce vast amounts of leaf litter, which decomposes, providing nutrients taken up by plants and fungi. Animals produce waste that is degraded on the rainforest floor. Legumes in the rainforest have root nodules with nitrogen-fixing bacteria, crucial for nitrogen cycling.

Explain the function of EACH of the following microorganisms in maintaining tropical rainforest ecosystems as self-sustaining units. You MUST present your response in complete paragraphs. Nitrifying bacteria, Denitrifying bacteria, Nitrogen-fixing bacteria.

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Other parts of this question

  1. 1(a)(i)List THREE products of the link reaction.[3 marks]
  2. 1(a)(ii)State the site of the link reaction.[1 mark]
  3. 1(a)(iii)Identify the name and function of the structures labelled Q, R and S in Figure 1.[6 marks]
  4. 1(a)(iv)Complete the diagram below to identify the reduced molecules produced. You MUST include the arrows to show where the molecules were produced in the Kreb's…[5 marks]
  5. 1(b)(i)State a suitable hypothesis for the experiment.[2 marks]
  6. 1(b)(ii)State a suitable control for the experiment.[1 mark]
  7. 1(b)(iii)Identify the manipulated and responding variable in this experiment.[2 marks]
  8. 1(b)(iv)Using the data in Table 1, identify which of the two beans respired faster.[1 mark]

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