4. Where does a magnetic field occur in relation to an electrified wire. a At either end. but no in the middle
b. Only on the side closest to the source
of electricity
c. Around the entire length of the wire
d. Only on the side furthest frou the source of electricity

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.