- 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.
The expected and observed ratios of offspring of the cross are given.
(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]