Answer: Carbohydrates in the form of glucose and oxygen as byproduct.
Step-by-step explanation:
Photosynthesis is a process which occurs in green plants and in other autotrophs. In this process the autotrophs can prepare their own food by using reactants like water and carbon dioxide to produce glucose which is a carbohydrate which a major source of energy for plants and oxygen gas is released as a byproduct of this chemical reaction. On the contrary to this the cellular respiration can be defined as the process in which the biochemical oxidation of food occurs and energy is released in the form of ATP and carbon dioxide and water are produced.
Thus in photosynthesis the carbon dioxide and water are the reactants whereas in cellular respiration they are the products.