Inheritance of wing shape and eye colour in the fruit fly, Drosophila melanogaster, is controlled by two genes. • Gene N/n controls wing shape. Allele N for wrinkled wings is dominant to allele n for normal wings. • Gene E/e controls eye colour. Allele E for rosy eyes is dominant to allele e for red eyes. A biologist predicted that, if the genes are on different chromosomes, the ratio of the phenotypes of the F2 generation would be 9:3:3:1. The biologist carried out a breeding experiment. • Homozygous dominant fruit flies with wrinkled wings and rosy eyes were crossed with homozygous recessive fruit flies with normal wings and red eyes. • All the F1 fruit flies had wrinkled wings and rosy eyes. • The F1 fruit flies were crossed with each other. [Table 2.1] shows the results for the F2 generation.