5. In fruit flies (Drosophila melanogaster), the allele for brown body (B) is dominant to black body (b) and the allele for long wings (L) is dominant to short wings (l). A dihybrid cross was made between a fruit fly heterozygous for both traits and a black, short‑winged fruit fly, as shown in the image.
(a) Explain the differences between the expected and observed phenotypic ratios of the cross. [3]
(b) Fruit flies are sometimes kept in enclosed glass mesocosms to study their population dynamics, genetics and interactions with the abiotic environment. Explain the advantages of using mesocosms in these studies. [2]
(c) Outline the experiment carried out by Hershey and Chase that provided evidence that DNA is the genetic material in organisms.
[3]