Use the following information to answer the question.
$$\begin{array} { c c c }
\text { Sex } & \text { Phenotype } & \text { Number } \
\text { male } & \text { wild } & 123 \
\text { male } & \text { yellow } & 116 \
\text { female } & \text { wild } & 240
\end{array}$$
In a Drosophila experiment, a cross was made between homozygous wild-type females and yellow-bodied males. All of the resulting F?s were phenotypically wild type. However, adult flies of the F? generation (resulting from matings of the F?s)had the characteristics shown in the figure. How is the mutant allele for yellow body inherited?
A) It is not X-linked.
B) It is X-linked.
C) It is inherited by X inactivation.
D) It is Y-linked.

Question

Use the following information to answer the question.
$$\begin{array} { c c c } 
\text { Sex } & \text { Phenotype } & \text { Number } \
\text { male } & \text { wild } & 123 \
\text { male } & \text { yellow } & 116 \
\text { female } & \text { wild } & 240
\end{array}$$
In a Drosophila experiment, a cross was made between homozygous wild-type females and yellow-bodied males. All of the resulting F?s were phenotypically wild type. However, adult flies of the F? generation (resulting from matings of the F?s)had the characteristics shown in the figure. How is the mutant allele for yellow body inherited?
A) It is not X-linked.
B) It is X-linked.
C) It is inherited by X inactivation.
D) It is Y-linked.

Quizplus · Accepted Answer

The fact that all F1 flies were phenotypically wild-type indicates that the wild-type allele is dominant to the mutant yellow body allele. However, in the F2 generation, both wild-type and yellow-bodied flies were observed, and the yellow body phenotype was present only in males. This pattern of inheritance is consistent with X-linked recessive inheritance, as males only inherit one X chromosome and therefore only need one copy of the mutant allele to express the phenotype.

Use the Following Information to Answer the Question In a Drosophila Experiment, a Cross Was Made Between Homozygous