Final answer:
Photosynthesis adds oxygen to and removes carbon dioxide from the atmosphere, while cellular respiration does the opposite, thereby maintaining a balance in the carbon cycle.
Step-by-step explanation:
Photosynthesis enriches the atmosphere with oxygen and cellular respiration increases the levels of carbon dioxide in the atmosphere. Photosynthesis and cellular respiration are integral to the carbon cycle, one of the fundamental processes of the biosphere. Photosynthesis uses energy, usually from sunlight, to convert carbon dioxide and water into glucose and oxygen, a process vital for the energy needs of plants and other organisms. On the contrary, cellular respiration takes in oxygen to metabolize carbohydrates, such as glucose, and releases carbon dioxide and water, which are then used in photosynthesis.
These two processes are effectively two sides of the same coin with the equation for cellular respiration being the direct opposite of photosynthesis. The exchange of carbon dioxide and oxygen through photosynthesis and cellular respiration worldwide helps to keep atmospheric oxygen and carbon dioxide at stable levels. The glucose made in photosynthesis is used in cellular respiration to produce ATP. Water is broken down to form oxygen during photosynthesis, whereas in cellular respiration oxygen is combined with hydrogen to form water.