CAIE A Level Biology 9700 · Infectious diseases
In a rural region, a cholera outbreak occurs after heavy rains flood the main water source. Health officials propose installing a clean water supply system. Explain how the transmission of cholera is linked to water contamination and why providing clean water is an effective control strategy, considering biological, social, and economic factors.
6 marks, so the mark scheme is looking for about 6 separate creditworthy points. Making the same point twice in different words earns it once.
Explain means: Give the reasons or the mechanism: why or how something happens. Link each point to the next with because, so or which means. A list of facts with no links usually loses the reasoning marks.
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