To make the molecules smaller, are added to the food.

If the experiment was perfomed more then once and you get the same results

Cuz i said so. which gives it to b

Mitochondria produce atp, a high energy compound. atp is used for all sorts of enzyme-mediated reactions, such as making proteins/nucleotides/etc, certain compounds cross the cell membrane, muscles move, etc.  without this source of energy, a cell will die. it will not be able to repair itself, defend against pathogens, etc.