Describe the carbon cycle.

Carbon is constantly being removed from and released into the environment, in the form of carbon dioxide. Hence, the carbon dioxide concentration in the environment remains relatively constant. The various processes by which carbon, in the form of carbon dioxide, is removed from and released into the environment make up the carbon cycle.

1. During photosynthesis, carbon dioxide is absorbed from the atmosphere by green plants and used to manufacture carbohydrates, for example, glucose.


2. Glucose may be changed to other organic ocmpounds such as fatx, amino acids and proteins.


3. When animals feed on green plants, the carbon compounds become part of the bodies of these animals. On the other hand, the carbon compounds may also be preserved in fossil fuels such as coal, natural gas and oil.

Release of carbon dioxide into the environment

Carbon dioxide is released into the environment through:

• Respiration: As living organisms respire , carbon compunds such as glucose are broken down in their bodies and thus carbon dioxide is released into the environment.


• Combustion: When fossil fuels like coal and natural gas are burnt or undergo combustion, carbon compounds that were preserved in the fossil fuels are broken down and carbon dioxide is released into the environment.


• Decay: The bodies of organisms decay when they die, which, in turn, are broken down into simple substances by decomposers. Carbon dioxide is one of the simple substances are absorbed by decomposers and become part of their bodies. When the decomposers respire, carbon dioxide is released into the environment.

The carbon cycle is important because it ensures that there is a continuous supply of carbon dioxide for plants to carry out photosynthesis. Photosynthesis converts energy from the sun into chemical energy in food, which other non-photosynthetic organisms can use to stay alive. The carbon cycle also enables energy to flow through the ecosystem. Carbon compounds carry the trapped solar energy from organism to organism in the food chain of an ecosystem.

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