Controlling endemic diseaseEdexcel A-Level Biology B: Mind map

Exam questions on Controlling endemic disease

1. In a trial in a malaria-endemic region, researchers gave insecticide-treated bed nets to the families in 20 villages. Another 20 similar villages received no nets during the trial and were given nets afterwards. Before the trial, the average number of malaria cases per 1000 children per year was 310 in the villages that were given nets and 300 in the other villages. One year later it was 140 in the villages with nets and 290 in the other villages.
   Calculate the percentage reduction in malaria cases per 1000 children in the villages that were given nets.2 marks
2. A government decides to spray the inside walls of homes with the insecticide DDT to kill Anopheles mosquitoes. DDT is cheap and very effective at first, but it persists in the environment and accumulates in food chains. In some districts the mosquitoes are no longer killed by it.
   Suggest why the spraying programme may become less effective over time.2 marks
3. A pharmaceutical company announces that its new malaria vaccine prevents most cases in children. At the same time, a separate research group proposes releasing genetically modified male mosquitoes whose offspring do not survive, in order to reduce the number of Anopheles mosquitoes in one region.
   Describe how the scientific community would validate the claim that the new vaccine is effective.3 marks