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1 markWater and the Aquatic Environment

CSEC Integrated Science · 2005 · Paper 2 · Question 4(a)(iii)

The local water supply in an area has become contaminated.

State one route by which treated water from a plant can become contaminated before reaching a household tap.

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Other parts of this question

  1. 4(a)(i)Explain why all drinking water from this contaminated supply should be boiled before drinking.[1 mark]
  2. 4(a)(ii)State whether it is necessary to boil water intended for making ice, providing one reason for your answer.[2 marks]
  3. 4(a)(iv)Identify one water-borne disease humans can contract by drinking contaminated water.[1 mark]
  4. 4(b)(i)a)Explain why a sterile swab was used in step one.[1 mark]
  5. 4(b)(i)b)Explain why bacteria were collected specifically from the mouth.[1 mark]
  6. 4(b)(i)c)Explain why the third agar plate was not treated with any mouthwash.[1 mark]
  7. 4(b)(i)d)Explain why the culture plates were incubated at 37 °C.[2 marks]
  8. 4(b)(ii)Identify which agar plate exhibited the highest amount of bacterial growth based on Figure 7.[1 mark]
  9. 4(b)(iii)Suggest what caused the high bacterial growth rate observed in the plate identified in (b)(ii).[1 mark]
  10. 4(b)(iv)State which brand of mouthwash is more effective, giving one reason from the results.[2 marks]
  11. 4(b)(v)State which mouthwash label in Figure 6 makes the more accurate claim based on the experimental results.[1 mark]

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