What do the cells need for respiration?
When active your cells need Oxygen and Glucose, Amino acids and Fatty acids [i.e. biochemical energy] to convert it to another "type" of energy, that can be used for biological reactions. Someone could call it molecular energy stored in the molecule ATP. Apart from organisms [like ours] that use oxygen as a final electron acceptor in respiration [which are described as aerobic], there are also those that do not use oxygen and are referred to as anaerobic.