Chapter 4, Problem 26P

Two pure-breeding strains of summer squash producing yellow fruit, ${\text{Y}}_{\text{1}}$ and ${\text{Y}}_{\text{2}}$, are each crossed to a pure-breeding strain of summer squash producing green fruit, ${\text{G}}_{\text{1}}$, and to one another. The following results are obtained:

a. Examine the results of each cross and predict how many genes are responsible for fruit-color determination in summer squash. Justify your answer. b. Using clearly defined symbols of your choice, give the genotypes of parental, ${\text{F}}_{\text{1}}$, and F2plants in each cross. c. If the ${\text{F}}_{\text{1}}$ of Crosses I and II are mated, predict the phenotype ratio of the progeny.