Is all of Earth's carbon dioxide supply constantly being used by organisms?

No, all of Earth's carbon dioxide supply is not constantly being used by organisms. While some carbon dioxide is used by organisms through processes like photosynthesis, respiration, and decomposition, a significant portion of carbon dioxide is also found in the atmosphere, oceans, and rocks. The carbon cycle is a natural process that involves the continuous exchange and cycling of carbon between the atmosphere, land, plants, animals, and living organisms.