Step-by-step explanation:
Let R be the allele for red stripes.
Let r be the allele for yellow stripes.
Parental phenotypes:
Orange stripes * Orange stripes
Parental genotypes:
Rr * Rr
Gametes:
(R)(r) * (R)(r)
Using a Punnett's Square, we get
F1 generation genotypes:
RR : Rr : rr = 1 : 2 : 1
F1 generation phenotypes:
Red : Orange : Yellow = 1 : 2 : 1.