Answer:
The substances that must be present for cellular respiration to occur are oxygen, enzymes, and organic molecules.
Explanation:
Cellular respiration is a process in which organic molecules are oxidized and production of ATP (adenosine triphosphate) occurs, which is used by living beings to meet their energy needs. Cellular respiration only occurs in the presence of oxygen, so this substance is inaccurate for this cellular process. The whole process of cellular respiration occurs with the action of enzymes that use an organic molecule as a substrate to create another molecule necessary for the cellular respiration process. For this reason, we can say that enzymes and organic molecules are also indispensable substances for cellular respiration.
