Cells on the shaded side of a plant stem elongate more than cells on the lighted side because __________. ethylene inhibits the cells on the lighted side from becoming more flexible auxins accumulate on the shaded side and cause the shaded side's cells to become more flexible ethylene stimulates cell growth on the shaded side and causes the cells to become more flexible auxins accumulate on the lighted side and cause the lighted side's cells to become less flexible