Which organoid generates the energy used by the cells?

These are mitochondria. They are characteristic of most eukaryotic cells. They are needed for the third stage of energy exchange, which occurs both in autotrophic cells and in heterotrophic cells. It is called the oxygen stage because oxygen is needed to oxidize organic molecules and release energy. Energy is stored in the form of ATP. To obtain it, mitochondria use primarily carbohydrates and fats. When these substances run out, the oxidation of proteins begins to obtain energy.