Amouse sees a hawk fly overhead. the mouse then runs into the nearest hole in the ground. what is the hawk flying overhead in this scenario?
a)a stimulus
b)a response
c)a developmental change
d)a unicellular organism

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.