Does one ripe apple really speed up ripening in the apples around it? Plants use a gas hormone called ethylene to signal when fruit should ripen. One ripe apple releases ethylene that can trigger nearby fruit to ripen faster. You test ripeness using an iodine staining method. Cut an apple in half and soak the cut face in iodine solution. Unripe apples contain starch, which turns black with iodine. As the fruit ripens starch converts to sugar. The dark stain fades. Design experiments to test how ripe and unripe apples interact. Place them together in sealed bags and score ripeness over time. Compare results against apples stored alone to measure how ethylene from one fruit affects the rest.