What is the role of plants in the carbon cycle?

Carbon is Absorbed by Plants

Plants absorb carbon (C), in the form of carbon dioxide (`~CO_2` ), into their cells from the atmosphere. 

The plants then use the absorbed `~CO_2` in the chemical process of photosynthesis. During photosynthesis, plants use energy from the sun and combine `~CO_2` with water to form sugar (`~CH_2O` ) and oxygen (`~O_2` ), as shown in the reaction below:

     `~CO_2 + ~H_2O + ` energy `-gt ~CH_2O + ~O_2`

Carbon is Released by Plants

Plants return carbon to the atmosphere in the form of carbon dioxide  (`~CO_2)` . This can occur four ways:

1. Plants break down the sugar for energy and release carbon dioxide.


2. Animals eat plants, break down the sugar for energy, and release carbon dioxide.


3. Plants die and decay. During the decay process, bacteria eat the dead plants, break down the sugar for energy, and release carbon dioxide .


4. Plants are destroyed by fire. When plants are burned, the sugar combines with oxygen to release carbon dioxide.  .

All four of these processes occur according to the chemical reaction below:

       `~CH_2O + ~O_2 -gt ~CO_2 + ~H_2O +` energy

Once carbon dioxide is released back into the atmosphere, the carbon cycle begins again.

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