| A | B |
|---|
| Photosynthesis | Plants trap carbon from carbon dioxide in sugars |
| Decomposition | Carbon from organisms is put into the ground when they die. |
| Deposition | Carbon in the ground gets condensed into fossil fuels. |
| Volcanic activity | An abiotic (non-living) way carbon dioxide ends up back in the atmosphere. |
| Carbon dioxide | Most carbon in the atmosphere is found in this molecule. |
| Combustion | Burning of fossil fuels to convert carbon to carbon dioxide. |
| Cellular respiration | Humans convert carbon in sugar to carbon dioxide. |
| Feeding | How humans get carbon. |
