Photosynthesis and cellular respiration are two complementary biological processes that occur in living organisms. Photosynthesis is the process by which plants, algae, and some bacteria convert light energy into chemical energy in the form of glucose and other organic compounds ,In contrast, cellular respiration is the process by which cells break down glucose and other organic compounds to release energy in the form of ATP , Photosynthesis primarily occurs in plants, photosynthetic bacteria, and algae, while respiration occurs in animals ,Another major difference between the two processes is that photosynthesis uses light energy to produce carbohydrate molecules, while respiration uses the energy stored in carbohydrate molecules ,Photosynthesis produces oxygen as a by-product, which is used in cellular respiration to generate ATP, while cellular respiration produces carbon dioxide as a by-product, which is used in photosynthesis to produce glucose ,In summary, photosynthesis and cellular respiration are two opposite processes that complement each other in the environment, and they are both essential for the survival of living organisms