Which of the following best describes the role of organisms in the carbon cycle?

Organisms play a critical role in the carbon cycle primarily through the processes of photosynthesis and respiration. In photosynthesis, plants, algae, and some bacteria convert carbon dioxide from the atmosphere into organic matter, using sunlight as an energy source. This process not only sequesters carbon, reducing the amount of carbon dioxide in the atmosphere, but also forms the basis of the food chain, as these organisms serve as primary producers for herbivores and higher trophic levels.

On the other side, respiration occurs in nearly all living organisms, including plants, animals, and decomposers. During respiration, these organisms break down organic matter, releasing carbon dioxide back into the atmosphere as a byproduct. This dual role ensures that carbon is continuously cycled through various forms, maintaining the balance within the ecosystem.

This comprehensive involvement in both capturing and releasing carbon indicates that organisms are indispensable to the carbon cycle, influencing not just local ecosystems but also global climate patterns.