if something is required by a living thing to perform a process then that living thing uses that something to perform that process
living_organism is living_thing. living_thing is not tangible_thing. humans is living_things. living_thing is whole. life is living_thing. living_thing is living_or_fictional_thing. aerobic_thing is living_thing. living_thing is tangible_thing. aerobic_thing is not living_thing. organism_part is living_thing.