just to get you started, they might expect you to know that the heterozygous form of sinkle cell anemia, in africa, is resistance to malaria. Also, a lot of poeple don't realise that beta thalassemia , in the mediterrean work the same way. both these disease are a mutation that if you are a heterozygous carrier your blood or body is slightly different to normal so you are less likely to get malaria than those who dont carry. as a result, the number of carriers increased as malaria killed off thse who didnt carry this gene, so now sometime babies inherit the gene from both parents, which give them the full blown disease- a very bad blood disease- but of course their parents and grandparents had been selected by natural selection due to the gene- look it up.
