(a)[4]
Explain how natural selection operated in the non-sprayed populations so that the mean concentration of natural insect-deterring chemicals increased.
(b(i))[1]
Identify the type of natural selection that made the mean concentration of insect-deterring chemicals rise in the non-sprayed populations.
(b(ii))[1]
Identify the type of natural selection that kept the flowering period unchanged in the non-sprayed populations.
(c)[2]
All of the non-sprayed populations showed the same pattern in the results. Explain how this supports the researchers’ conclusion that natural selection caused the patterns and not genetic drift.