(a)[4]
Outline how selective breeding has been employed to improve maize.
(b)[3]
Fig. 4.1 shows a section of a maize cob. The cob contains many separate seeds called kernels. Each kernel is formed by a separate fertilisation of one male and one female gamete. Some kernels are yellow and some are purple. Name the type of variation shown in Fig. 4.1. Suggest a genetic explanation for this colour pattern.
(c(i))[4]
Describe how the number of resistant pest species changes with the area of Bt crops grown and suggest an explanation for this relationship.
(c(ii))[2]
Suggest one social advantage and one environmental advantage of cultivating this Bt maize.