Purebreed lines of fruit flies with wild type (tan) body color and stubbly brist

Question

Purebreed lines of fruit flies with wild type (tan) body color and stubbly bristles are mated to flies with ebony bodies and normal bristles. The resulting F1 offspring all have normal wild-type body color and stubbly bristles. The F1 flies are crossed with flies recessive for both traits (i.e. ebony bodies and normal bristles).

Assume you found the following results amount offspring:

Wild,stubby bristles 424

ebony, stubby bristles 58

wild type body,normal bristles 62

ebony body,normal bristles 456

How would you explain these results?

Explanation / Answer

Because the result of the F1 (first cross) was Stubby and Tan, you know that the dominant alliel gives Stubby and Tan phenotypes (because SS x ss -> Ss = Stubby Heterozygous) (TT x tt -> Tt = Tan Heterzygous)

Now we know this, the F2 gen's parents both have:
Tt Ss
Tt Ss
So....
T x t x T x t = TT, Tt, Tt, tt ( thats 1 homozygous Tan, two heterozygous Tan, and one homozygous Ebony)
Therefore the ratio of Tan to Ebony is 3:1.

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