Final answer:
The fly's phenotype with an X:A ratio of 1.0 and the given genotype is female, with dominant traits such as wild-type phenotype being inherited as per Mendelian genetics. The traits are linked to the X chromosome, influencing the offspring's genotypes and phenotypes in predictable patterns.
Step-by-step explanation:
The phenotype of a fly with an X:A ratio of 1.0 and the specified genotype (Sxllf/ Sxllf tralf/ tralf dsxnulllf/ dsxnulllf) would be female. This is because the X:A ratio determines sex in Drosophila, and a ratio of 1.0 typically indicates a female. Concerning the cross between a true-breeding wild-type male fly and a true-breeding female fly with a black body and cinnabar eyes, where all F1 progeny displayed a wild type phenotype, it indicates that the traits for the wild-type phenotype are dominant and the reciprocal cross resulted in the traits being passed on in a Mendelian fashion.
The traits in question are associated with the X chromosome in Drosophila. Females can be homozygous or heterozygous for these traits, while males, being hemizygous, display the trait of the single X chromosome they possess. Thomas Hunt Morgan's work showed that in a cross involving X-linked traits, such as eye color in fruit flies, the genotypes and phenotypes of the offspring can vary depending on the parental genotypes. For example, crossing a homozygous red-eyed female with a white-eyed male would result in all red-eyed F1 progeny, with subsequent generations having a mix of red- and white-eyed individuals depending on the specific crosses.