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3 marksPhotosynthesis and ATP Synthesis

CAPE Biology Unit 2 · May/June 2022 · Paper 2 · Question 1(b)(iv)

A farmer is planning to investigate the effect of different types of energy efficient LED bulbs on lettuce in a greenhouse under artificial light. The procedure involves germinating seeds, washing plantlet roots, placing 20 plantlets in each of three hydroponic units with the same nutrient solution, subjecting units to different LED light treatments (red:blue ratios of 0.5, 1.0, 2.0, all 60-watt equivalent), and harvesting and weighing plants after 18 days.

Explain how growing lettuce in a greenhouse using a hydroponic system can reduce the effects of ONE limiting factor of photosynthesis.

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Other parts of this question

  1. 1(a)(i)Define the term 'limiting factor'.[2 marks]
  2. 1(a)(ii)Outline how light intensity is a limiting factor in the process of photosynthesis.[2 marks]
  3. 1(b)(i)State a suitable hypothesis for the investigation.[2 marks]
  4. 1(b)(ii)Identify ONE manipulated variable and ONE responding variable in the investigation.[2 marks]
  5. 1(b)(iii)State ONE variable that should be controlled in the investigation.[1 mark]
  6. 1(c)(i)Define the term 'species diversity'.[2 marks]
  7. 1(c)(ii)Explain how high species diversity affects the stability of an ecosystem.[3 marks]
  8. 1(d)(i)Classify EACH of the following factors as EITHER an abiotic factor or a biotic factor. Ocean currents, The lionfish as predators, The lionfish feeding on…[4 marks]
  9. 1(d)(ii)Explain how any THREE of the factors in (d)(i) influenced the dynamics of the coral reef ecosystem since the invasion of the lionfish.[9 marks]

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