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Carbon? ... Who Needs Carbon?

This diagram above looks a lot like a food chain, right? You could think of the arrows showing the direction of energy, but let's think of it another way...

Notice that the arrows go in a clockwise direction. Therefore, this is more of a “continuous” cycle which will repeat again and again. So just what are you looking at?

If you said The Carbon Cycle, then you are correct. Your human body contains 18 percent carbon. For a plant to form simple sugars, or carbohydrates, it needs carbon dioxide and water. We need carbohydrates for energy, so we consume plants and animals that consume plants. This allows us to obtain the elements we need.

When we consume the plants, our body breaks down the sugar, and the carbon is released for our body’s use. Some carbon is also released to the atmosphere as we exhale from breathing and also as organic materials decay..

Let's take a look at how carbon gets from one place to another, and the form by which it travels.

Carbon dioxide (CO2) is the major source of carbon in the atmosphere. 99.6% of the carbon in the atmosphere is in this form. Plants take in CO2 during the process of photosynthesis, along with water vapor, to form oxygen and glucose. Glucose, a sugar, is an organic molecule, which means it contains carbon.

Animals eat plants for energy, and in the process the carbon atoms in the glucose get converted into another form during the process of respiration. Glucose and oxygen react to produce carbon dioxide, which is released back into the atmosphere. Carbon is also incorporated into many of the different molecules needed by living things to grow, repair and reproduce.

Once an organism dies, what happens to the collection of the countless atoms that make up the body? In particular, what happens to the carbon atoms? Decomposers break down the complex molecules into simpler substances. Carbon dioxide is again released into the atmosphere, where the carbon cycle can start over again.



Let's see if you can remember the main ideas of this page. Identify what form or process each box is referring to, and click on the box to check your understanding.

stores carbon in

is captured
by plants by
release carbon in
Plants store
carbon in
store carbon in
is taken in
by animals by
is taken in by
decomposers by
store carbon in
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Updated October 24, 2008 by: Glen Westbroek

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