Why mitochondria is compared with the power house?

The main function of mitochondria is to help an organism produce energy from food through cellular respiration. A series of biochemical reactions of Kreb's cycle occurs on the mitochondria of a cell. Another series of biochemical reactions occur through the electron transport chain, a series of electron carriers in the inner membrane of mitochondria. In the process, energy is, ultimately, produced. This is why a mitochondrion is called 'the power house' of a cell.