The allele Y in Drosophila is a dominant allele that is lethal when homozygous,
ID: 144844 • Letter: T
Question
The allele Y in Drosophila is a dominant allele that is lethal when homozygous, but gives flies a yellow body color in the heterozygous condition with y, an allele for wild-type (brown) body color. At a second locus, the allele B for long bristles is incompletely dominant to the allele b for short bristles. Both loci are autosomal. If you cross two yellow body, medium bristled flies with each other, what is the probability that one of the offspring will have the same phenotype as the parents? Answer to two decimal points. NumberExplanation / Answer
Yy Bb X Yy Bb
Yellow colour and medium bristles x Yellow colour and medium bristles
Yy x Yy
yellow x yellow
2/4 or 1/2 -yellow coloured(Yy) progenies resemble their parents
Bb x Bb
2/4 or 1/2 progenies(Bb) resembles their parental phenotypes of having medium bristles.
Thus progenies similar to parental types are-
1/2 x 1/2 =1/4 = 0.25
Y y Y YY Yy y Yy yy