During photosynthesis, the plant needs carbon dioxide and water-- both of which are released into the air during respiration, during respiration, the plant needs oxygen and glucose, which are both produced through photosynthesis
The reactants of one process are the products of the other process. For example, carbon dioxide, produced by cellular respiration, is one of the reactants for photosynthesis. Photosynthesis produces glucose and oxygen. Glucose and oxygen are used by many organisms for cellular respiration.
