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6 marksPhotosynthesis and Energy Flow

CSEC Human and Social Biology · January 2008 · Paper 2 · Question 12(b)(i)

An island introduces weedicide to clear seaweeds for tourism, resulting in weedicide poisoning in humans.

Explain how weedicide accumulated to toxic levels in humans by analyzing its concentration across each trophic level of the marine food chain.

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Other parts of this question

  1. 12(a)(i)Identify which trophic position in a food chain (beginning, middle, or end) possesses the greatest amount of energy.[1 mark]
  2. 12(a)(ii)Identify at which point in a food chain photosynthesis takes place.[1 mark]
  3. 12(a)(iii)Construct a food chain showing the correct sequence among: big fish, water weed, small fish, and tadpole.[3 marks]
  4. 12(b)(ii)Explain how the physical removal of seaweed caused the collapse of marine life and death of local coral reefs.[6 marks]
  5. 12(c)Explain how agricultural runoff from farming near a river can result in the biological death of the river (eutrophication).[3 marks]

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