Final answer:
Mitochondria are membrane-enclosed organelles responsible for producing ATP through cellular respiration. They are known as the "powerhouses" of the cell.
Step-by-step explanation:
Mitochondria are membrane-enclosed organelles found in most eukaryotic cells. They are known as the "powerhouses" or "energy factories" of the cell because they produce adenosine triphosphate (ATP), the cell's main energy-carrying molecule, through cellular respiration. ATP is used for various processes in the cell, such as movement and cell division. Mitochondria use energy from organic compounds to make ATP, and this process requires oxygen and produces carbon dioxide as a waste product.