What is the first step in the carbon cycle?

The first step in the carbon cycle involves the movement of carbon from the atmosphere into living organisms and is primarily facilitated by photosynthesis. In this process, carbon dioxide (CO2) from the atmosphere is absorbed by plants, algae, and some bacteria to produce oxygen and organic compounds like glucose. This process is fundamental to the carbon cycle because it establishes the base of the food web, allowing carbon to enter living organisms.

While giving off CO2 through respiration and combustion is significant in the carbon cycle, this process does not initiate the cycle itself. Rather, it is part of the ongoing exchange of carbon between the atmosphere and living beings. Phosphorus dissolving in water is unrelated to the carbon cycle and pertains more to the phosphorus cycle, emphasizing the need to focus on carbon processes. Therefore, the involvement of photosynthesizing organisms in capturing atmospheric CO2 is correctly identified as the first step in the carbon cycle.