A dominant allele H at the H locus reduces the number of body bristles that Drosophila flies have, giving rise to a âhairlessâ phenotype. In the homozygous condition, H is lethal. An independently assorting dominant allele S has no effect on bristle number except in the presence of H, in which case a single dose of S suppresses the hairless phenotype, thus restoring the hairy phenotype. However, S also is lethal in the homozygous (S/S) condition.
A. What is the phenotype of a dihybrid (H/h; S/s)?
B. What is the phenotype of an H/h; s/s fly?
C. Suppose you mated a H/h; s/s female with an h/h; S/s male. What phenotypic ratios would you expect in the living offspring? ****For part C I got 2/16 hairless, 7/16 hairy, and 7/16 not living
D. A true-breeding plant of genotype A/A; B/B; c/c is crossed to a truebreeding plant of genotype A/A; b/b; C/C. What would be the genotype and phenotype of the F1?
