The Carbon Cycle

plants pull carbon from the air and animals eat the plants Carbon (C) is the basis of life on Earth. Scientists consider 99.9% of all organisms on the planet to be carbon based life. Those organisms need carbon to survive. Whether the carbon is in the form of a sugar or carbon dioxide gas, we all need it. Unlike energy, carbon is continuously cycled and reused. The Earth only has a fixed amount of carbon. The carbon cycle is the ultimate form of recycling.

Start With Plants

Plants are a good starting point when looking at the carbon cycle on Earth. Plants have a process called photosynthesis that enables them to take carbon dioxide out of the atmosphere and combine it with water. Using the energy of the Sun, plants make sugars and oxygen molecules. All of the non-photosynthetic creatures on the planet use the oxygen. Every creature on the planet uses the sugars and starches created by plants.

Then Animals Eat The Plants

Animals are the non-photosynthetic creatures of the planet. They are not able to create their own food. Instead, they eat plants or other animals. The sugars and starches they eat are broken down by a process of metabolism. The results are energy for the creature, water, and carbon dioxide molecules. The carbon dioxide then returns to the atmosphere where the plants use it again.

carbon moving through living systems

Who Eats The Animals?

There are also decomposers involved in the carbon cycle. They break down organic material such as dead animals, poop, or leaves. Decomposers are able to break down the chemical compounds inside the body. They also release carbon dioxide as well as methane.

Sometimes the decomposers don't break down organic material. There are great oil fields under the surface that are made of plants that did not decompose millions of years ago. There are also layers of rock made of millions of creatures who had shells. One day this carbon will return to the everyday carbon cycle, but geological processes are much slower than living processes.

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Next page on the biogeochemical cycles.
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