(a) The fruit fly, Drosophila melanogaster, feeds on sugars found in damaged fruits. A fruit fly with normal features is described as wild type. It has red eyes and its wings are longer than its abdomen. There are mutant variations such as purple eyes or short (vestigial) wings. Fig. 7.1 shows a wild type fruit fly and a mutant fruit fly with purple eyes and vestigial wings. [Figure 7.1] • The genes coding for eye colour and wing length are located on the same chromosome. • Allele R for red eyes is dominant to allele r for purple eyes. • Allele N for long wings is dominant to allele n for vestigial wings. (b) A wild type fruit fly, heterozygous for both genes, was crossed with a fruit fly that was homozygous recessive for both genes.