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1 markEnergy Flow and Nutrient Cycling

CAPE Biology Unit 2 · 2003 · Paper 1 · Question 3(c)(iii)

Rainforest trees rely on mutualistic mycorrhizae for approximately 90% of their nitrogen, fixing N2 to NH4. Figure 3 shows nitrogen available to trees after infection with mycorrhizae over time.

On the graph in Figure 3 on page 7, draw a single line to illustrate the nitrogen that would be available to a rain forest tree that is NOT infected with mycorrhizae.

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Other parts of this question

  1. 3(a)State briefly what happens to a stable ecosystem when it is disturbed.[1 mark]
  2. 3(b)(i)Suggest the effects that removing Species A will have on the coral reef ecosystem.[2 marks]
  3. 3(b)(ii)Suggest the effects that removing Species B will have on the coral reef ecosystem.[3 marks]
  4. 3(c)(i)Explain why the nitrogen available to the rain forest is NOT zero units at the time of infection.[1 mark]
  5. 3(c)(ii)Suggest an explanation for the shape of the graph in Figure 3.[2 marks]

More practice: the rest of this paper · more Energy Flow and Nutrient Cycling questions · all CAPE Biology Unit 2 past papers