Answer:
Photosynthesis removes CO2 from the atmosphere and replaces it with oxygen.
Step-by-step explanation:
Photosynthesis removes CO2 from the atmosphere and replaces it with oxygen. By respiration, O2 is removed from the atmosphere and replaced with CO2. However, these processes are not balanced. Some organic matter is not oxidized. (I'm very sorry if I'm wrong but I believe it's that)