Final answer:
Cellular respiration refers to intracellular reactions that break down energy-rich molecules to form ATP and carbon dioxide. It occurs in all living organisms to provide usable energy. The reactants for cellular respiration are glucose and oxygen.
Step-by-step explanation:
Cellular respiration refers to a set of intracellular reactions in which energy-rich molecules are broken down to form ATP and carbon dioxide. It is a process that occurs in the cells of all living organisms, using glucose and oxygen as reactants. Through these reactions, cells obtain usable energy in the form of ATP to power other cellular processes.