In a Drosophila experiment, a cross was made between homozygous wild-type females and yellow-bodied males. All of the resulting F 1 s were phenotypically wild type. However, adult flies of the F 2 generation (resulting from matings of the F 1 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

In a Drosophila experiment, a cross was made between homozygous wild-type females and yellow-bodied males. All of the resulting F 1 s were phenotypically wild type. However, adult flies of the F 2 generation (resulting from matings of the F 1 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 individuals were wild-type indicates that the yellow body allele was recessive. However, in the F2 generation, both males and females exhibited the yellow-bodied phenotype, but this trait was more common in males. This is a typical pattern for X-linked inheritance, where a recessive allele carried on the X chromosome will be expressed in males because they only have one X chromosome. Therefore, the mutant allele for yellow body is X-linked.

In a Drosophila Experiment, a Cross Was Made Between Homozygous