In a standard monohybrid cross between purple-flowered and white-flowered peas, in which purple flowers are dominant, what fraction of the purple-flowered peas in the F2 generation would you expect to be true-breeding?

75% of the progeny contains purple flower in F2 generation.

Explanation:

The cross between the purple and white flower can be done by the following ways:

(Parents) PP (purple flower) * pp (white flower)

(Gametes) P p

F1 genereation Pp (purple flower)

Selfing of F1 genereation : Pp * Pp

Progeny of F2 genereation are: PP (purple flower), Pp and Pp (purple flower) and pp (white flower).

The phenotype ration of purple to the white flower is 3:1 or 75% of total progeny is purple flowered.

Thus, the answer is 75%