Bananas grow in bunches. Like other fruit, ethylene gas produced by ripening bananas speeds up the ripening process.
I read that leaving bananas attached to their stem speeds up their ripening process. Is this really true? How could you find out?
This would make a great science project. Just make sure that all the bananas being tested are at the same stage of ripening. Also, since bananas connected to the stem touch each other, you would have to place separated bananas in a similar position.
For more information about fruit ripening, see Fruit Ripening.