Amutation results in an organism that lacks the ability to make one amino acid. what caused this mutation

Astudent analyzed ears of corn that demonstrated two traits in the f2 kernels, purple or white colors and smooth on wrinkled shapes. a tabulation of 135 individual kernels gave the following results: purple and smooth = 75 white and smooth = 28 purple and wrinkled = 24 white and wrinkled = 8 what would be the only phenotype present in the f1 ger