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2 marksEnergy Flow and Nutrient Cycling

CAPE Biology Unit 2 · May/June 2025 · Paper 2 · Question 1(b)(ii)

In a mangrove ecosystem, algae harvest about 170 000 kJ m⁻² yr⁻¹ of sunlight energy. Crabs consume algae, harvesting about 12% of the energy obtained by the algae. Marine birds consume crabs, harvesting 10% of the energy obtained by the crabs.

Determine the productivity of the producer in the mangrove ecosystem if 1 000 000 kJ m⁻² yr⁻¹ of energy is provided by sunlight to the mangrove.

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Other parts of this question

  1. 1(a)(i)Name the THREE stages of the light-independent reactions that occur in the Calvin cycle, labelled X, Y and Z in Figure 1.[3 marks]
  2. 1(a)(ii)State the functions of reduced NADP+ and ATP in the light-independent reactions.[2 marks]
  3. 1(a)(iii)Outline a suitable procedure for conducting the investigation.[5 marks]
  4. 1(b)(i)Given the information above, construct a pyramid of energy with corresponding values for the mangrove ecosystem.[4 marks]
  5. 1(b)(iii)State TWO reasons why all the energy available from sunlight is not used by the algae.[2 marks]
  6. 1(c)(i)Define EACH of the following components of biodiversity: Species diversity, Genetic diversity, Ecosystem diversity.[3 marks]
  7. 1(c)(ii)Explain the impact of climate change on EACH of the following components of biodiversity. You MUST present your response in complete paragraphs: Species…[9 marks]

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