$\begin{array} { c c c } \text { Sex } & \text { Phenotype } & \text { Number } \\\text { male } & \text { wild } & 123 \\\text { male } & \text { yellow } & 116 \\\text { female } & \text { wild } & 240\end{array}$ Figure 14.1
-In a Drosophila experiment, a cross was made between homozygous wild- type females and yellow- bodied males. All of the resulting F₁s were phenotypically wild type. However, adult flies of the F₂generation resulting from matings of the F₁s) had the characteristics shown in the figure above:
A. Is the mutant allele for yellow body recessive or dominant?
B. Is the yellow locus autosomal not X- linked) or X- linked?

Question

\begin{array} { c c c } \text { Sex } & \text { Phenotype } & \text { Number } \\\text { male } & \text { wild } & 123 \\\text { male } & \text { yellow } & 116 \\\text { female } & \text { wild } & 240\end{array}

Figure 14.1
-In a Drosophila experiment, a cross was made between homozygous wild- type females and yellow- bodied males. All of the resulting F₁s were phenotypically wild type. However, adult flies of the F₂generation resulting from matings of the F₁s) had the characteristics shown in the figure above:
A. Is the mutant allele for yellow body recessive or dominant?
B. Is the yellow locus autosomal not X- linked) or X- linked?

Quizplus · Accepted Answer

The fact that all F₁ flies were phenotypically wild type indicates that they were homozygous for the wild-type allele. However, in the F₂ generation resulting from matings of these flies, some flies had yellow bodies, which indicates that they must have inherited a mutant allele from one of their F₁ parents. This would only be possible if the mutant allele is recessive, as the F₁ parent must have been homozygous for the wild-type allele. Additionally, the fact that the yellow-bodied flies were only found in the F₂ generation and not in the F₁ generation suggests that the yellow locus is not on the X chromosome, as X-linked traits usually show different inheritance patterns between males and females. Thus, the best choice is D) a) recessive; b) X-linked.

Figure 141 -In a Drosophila Experiment, a Cross Was Made Between

Figure 141
-In a Drosophila Experiment, a Cross Was Made Between