WHAT IS MEANT BY CARBON UNDERGOING CYCLIC CHANGE?

Carbon cycling is the continuous process by which carbon is exchanged between organisms and the environment. Carbon dioxide is absorbed from the atmosphere by plants and algae and converted to carbohydrates by photosynthesis. Living things also absorb carbon from carbonate rocks and ocean deposits (limestone and coral), or dead organic matter in the soil, or food. Carbon is then passed into the food chain after which carbon is returned to the atmosphere by respiration, combustion, or decay, in the form of carbon dioxide or methane. Thus carbon undergoes cycling in various forms (i.e. interconversion of carbon compounds in the environment)