Which of the following statements is true? Energy can be created, but not destroyed. Some machines are 100 percent efficient. Atomic energy can't be converted into electricity. When work is done, some energy is always "lost" as heat.

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.

Both prokaryotic and eukaryotic cells have ribosomes and cell membranes