* Oxygen (O2): This is the final electron acceptor in the electron transport chain, the process that generates the majority of ATP (energy) in aerobic respiration.
* Fuel molecules: These can be carbohydrates (like glucose), fats, or proteins, which are broken down to provide the energy for respiration.
* Water (H2O): This is used in some reactions within the process.
It's important to note that while the organism takes in these substances, it also releases other substances back into the environment during respiration, such as carbon dioxide (CO2) and water.
