Answer:
Photosynthesis removes CO2 from the atmosphere and replaces it with oxygen.
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)
We would have a hard time moving and your heart and other major organs would be easier to damage
Absorbing CO2 into the blood is a part of the respiratory system!