The fruit colours of summer squash may be white, yellow, or green. The determination of the phenotypic colour is an example of dominant epistasis. 

White fruit is produced by a dominant epistatic allele (W). At another location on the chromosome, the allele for yellow fruit (F) is dominant over the allele for green fruit (f). The presence of the white allele hides the effect of the yellow or green alleles. 

If a  cross occurs, 

1. predict the gametes
2. predict the F₁ generation offspring that will occur by creating a Punnett square, and
3. provide the white : yellow : green hybrid phenotypic ratio.

Answer:

1.      The four gametes are formed WF, Wf, wF, and wf.

2.      F₁ (filial first) generation offspring generated are 16 individuals with white, yellow, and green phenotypes.

3.      Phenotypic ratio for white: yellow: green is 12:3:1.

Step-by-step explanation

1.The pattern of inheritance is dominant epistasis, in which the dominant allele masks the phenotypic expression of other allele. In the given question, white (W) is dominant over yellow (F) and green (f), which means the presence of single allele of white will be expressing over other phenotypes. The gametes for the cross are WF, Wf, wF, and wf.

2.The cross made between WwFf x WwFf is shown in the attachment below:3.Thus, the phenotypic ratio for the cross is 12:3:1.

PFA