| A | B |
| The carbon cycle starts here. | Atmospheric carbon dioxide (CO2) |
| Atmospheric carbon dioxide (CO2) is used by | plants |
| Through photosynthesis plants make | carbohydrates |
| Carbohydrates are eaten by | animals |
| Animals use carbohydrates in | cellular respiration |
| Cellular respiration releases | atmospheric carbon dioxide (CO2) |
| Organisms die and after millions of years they form | fossil fuels |
| Humans burn fossil fuels to create | Excess atmospheric carbon dioxide (CO2) |