In the inhertance of colours in summer squash, white fruit colour is controlled by a dominant allele (W) and yellow fruit colour by the recessive allele (w). A dominant allele at another locus (S) produces disc-shaped fruit and its recessive allele (s) yields sphere-shaped fruit. If a homozygous white disc variety is crossed to a heterozygous white sphere variety and the F1, individuals are back crossed to the disc parent, determine the expected phenotypic ratio in the F2
