Genetics problem - genotypes and epistasis

[andydan1056]

https://scontent-ord1-1.xx.fbcdn.net/hphotos-xpf1/v/t1.0-9/11695990_871019416316266_5030432296478917772_n.jpg?oh=e6514207eea2317acc509cbb8d1382b0&oe=560E6C72 1. Homework Statement

Homework Equations

The Attempt at a Solution

I'm really not sure how to solve this or where to begin. I don't know which genotypes to use (YYyy or RRrr?). The ratios are familiar to me as a result of epistasis, but I don't know how to show the genotypes (a.) or explain how the F1 phenotypes and F2 ratios are produced (b.)

Could someone show me the process? Thanks![/B]

 

[Dr. Courtney]

You guess genotypes, work all the Punnett squares, and go with the answer whose Punnet squares predict the right phenotype ratios.