How does octopus 's method of transportation demonstrate the third law of motion.

This demonstrates the third law of motion because when the octopus propels the jet of water out it creates a force that pushes the octopus forward. ... For every action there is an equal and opposite reaction or forces occur in action and reaction pairs.

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.