Two true-breeding pea plants were crossed. One parent is round, terminal, and violet, constricted, while the other expresses the respective contrasting phenotypes of wrinkled, axial, white, and full. The four pairs of contrasting traits are controlled by four genes, each located on a separate chromosome. In the F1 only round, axial, violet, and full were expressed. In the F2, all possible combinations of these traits were expressed in ratios consistent with Mendelian inheritance.
a) In the F2 generation, how often is either of the P1 phenotypes likely to occur? Express your answer as a fraction?
b) If the F1 plants were testcrossed, how many different phenotypes would be produced? Express your answer as a whole number.