"a biology student decides to copy mendel’s experiment with pea plants. unfortunately, some of the pea plants from the p generation, the "true-breeding" plants, get mixed in with some of the f1 generation plants. the student attempts to sort out the plants by crossing two purple-flowered plants that are believed to be heterozygous f1 plants. the results of this cross produce 100 offspring of which 72 have purple flowers and 28 have white flowers. which of the following statements are true? "