Discuss the relationship between autotrophs and heterotrophs. do heterotrophs depend on autotrophs for the survival?

Heterotrophs depend on autotrophs to obtain energy from the sun. This energy is then passed on to heterotrophs in form of food. Without autotrophs, the sun's energy would not be available to heterotrophs and heterotrophs would eventually die out or find a new way of obtaining energy. hope this helps

Heterotrophs do require autotrophs for survival. If all of the autotrophs died, then the herbivores would die and the carnivores would eat themselves out of existence.

If it doesn't have a nucleus its a prokaryote

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.