In Drosophila,two Genes Affecting Body Color Are Known A)What Are the Genotypes of the Parents and the F₁

Essay

In Drosophila,two genes affecting body color are known.A mutant allele at one locus prevents the formation of granules on which pigment is laid down.An absence of these granules causes an albino.Another gene causes the color (the pigment involved)to be blood-red.True-breeding albino males were crossed to true-breeding blood-red females.All males and females in the resulting F₁ generation were wild type in appearance.Two F₁ flies were intercrossed,producing a large F₂ generation,with the following phenotypes.

$\begin{array}{lll}\text { Phenotypes } & \text { Observed numbers } & \text { Expected ratic } \\\text { Wild-type female } & 39 & \underline{\quad\quad}\\\text { Blood female } & 8 &\underline{\quad\quad} \\\text { Wild-type male } & 13 & \underline{\quad\quad} \\\text { Albino male } & 17 & \underline{\quad\quad}\\\text { Blood male } & \underline{3}& \underline{\quad\quad}\\\text { Total } &{80} &16\end{array}$
a)What are the genotypes of the parents and the F₁?
b)Given the F₁ genotypes in part a),fill in the expected phenotypic ratio for the F₂ in the spaces above.
c)Use the chi-square test to determine how well the observed ratio fits the expected ratio.