Two new mutant lines of a flowering plant have been obtained; one breeds true for blue flower color and the other breeds true for red flower color (wild-type flower color is purple). Consider the following crosses.
1. blue × purple → F1 all purple → F2 75% purple; 25% blue
2. red × purple → F1 all purple → F2 75% purple; 25% red
3. red × blue → F1 all purple
If the red pigment is a precursor of the purple pigment, the blue pigment is a precursor of the red pigment, and a colorless compound is the precursor of the blue pigment in a linear biosynthetic pathway controlling flower color, what phenotypic ratios do you expect in the F2 of cross 3?