In Drosophila, the recessive allele p, when homozygous, determines pink eyes.Pp or PP results in wild-type eye color.On the same chromosome of Drosophila that carries the p (pink eyes) locus there is another locus that affects the wings.Homozygous recessives, byby, have blistery wings, whereas the dominant allele By produces wild-type wings.The P and By loci are very close together on the chromosome; that is, the two loci are tightly linked.Assume that no crossing over occurs, and that the F₂ generation is produced by interbreeding the F₁ progeny.For the cross PPByBy * ppbyby, what is the genotype ratio of the F₂ generation? A) 3 PPByBy : 1 ppbyby B) 1 PPByBy : 3 ppbyby C) 1 PPByBy : 2 PpByby: 1 ppbyby D) 3 PpByby : 1 ppbyby E) 1 PpByby : 3 PPByBy

Question

Quizplus · Accepted Answer

Since the P and By loci are tightly linked and no crossing over is assumed, the F1 generation will have heterozygous genotypes for both traits (PpByby). When these F1 individuals are interbred, the expected genotypic ratio in the F2 generation, considering simple Mendelian inheritance and linkage, is 1 PPByBy : 2 PpByby : 1 ppbyby.

In Drosophila, the Recessive Allele P, When Homozygous, Determines Pink