Cambridge O Level Biology · Syllabus 5090 · Relationships of Organisms with One Another and with the Environment
Carbon Cycle
What is Carbon Cycle?
The circulation of carbon between the atmosphere and water, living organisms and long-term stores. Carbon dioxide is removed from air or water by photosynthesis and built into the organic molecules of producers; feeding transfers that carbon to consumers; respiration by plants, animals and decomposers returns carbon dioxide; death, waste and excretion pass organic carbon to decomposers, whose respiration also returns carbon dioxide; and some carbon is stored over geological time as fossil fuels, which release carbon dioxide when they are burned.
This definition is part of the Relationships of Organisms with One Another and with the Environment chapter in Cambridge O Level Biology.
Common mistakes with Carbon Cycle
- “Plants do not respire, so plant respiration is not part of the carbon cycle.” Why it is wrong: plants respire continuously, day and night, and release carbon dioxide. Exam-safe: respiration by producers, consumers and decomposers all return carbon dioxide to the air. Plant respiration is the arrow most often missed.