1. Carbon-Oxygen Cycle 1
These two linked cycles provide plants and animals with energy and materials for the basic building blocks of life. Carbon and oxygen have independent cycles but most often travel together. Carbon, oxygen, nitrogen and hydrogen are bonded together to form biomolecules (protein (R-NH2), carbs (CH2O), fats (CHO)). Carbon (C) is found in all living things in biomolecules. It is also found in the atmosphere as carbon dioxide (CO2). Oxygen (O2) makes up 21% of Earth’s atmosphere and is found dissolved in fresh and ocean waters.

2. 2
In the process of photosynthesis, plants take in water (H20) from the soil and carbon dioxide from the air. The water and carbon dioxide are converted into biomolecules such as sugars/carbohydrates. The by-product—oxygen– is released into the air.

3. 3
In the process of respiration, all living things (including plants) use oxygen to “burn” sugars. This produces water and releases carbon dioxide as a by-product into the air.

4. 4
Animals eat plants or other animals and break down the consumed organism’s complex biomolecules into simpler biomolecules. This releases energy that is now available for the consumer.

5. 5
Rocks contain calcium carbonate (CaCO3). In addition marine organisms such as shells, snails, pearls, all contain calcium carbonate. The bicarbonate (HCO3-) in the water is used to help make the shells and in reverse the shells release carbonate into the water.

6. 6
As land animals and plants die, decomposers use oxygen from the air or soil to break down the dead organisms’ carbon containing biomolecules. Carbon dioxide is released into the atmosphere.

7. 7
Over long periods of time, pressure from overlying soil or water can compress carbon from dead organisms into peat. It can then become fossil fuel (R-CH3) such as coal, natural gas (Methane = CH4), or oil. When humans burn fossil fuels, the carbon in the fuel combines with oxygen in the air. This releases carbon dioxide into the air.

8. 8
Photosynthetic phytoplankton in the ocean take carbon dioxide from the air or ocean water and incorporate the carbon into biomolecules. This releases oxygen.

9. 9
As aquatic animals and plants die, decomposers oxidize the dead organisms’ carbon compounds. This releases carbon dioxide into the ocean water. Organic material also sinks to the aquatic floor where, over time, the carbon can be compressed into fossil fuels (R-CH3).