1. The Carbon and Nitrogen Cycles

2. What is Carbon? Carbon is an element that is in all living things.
Molecules containing carbon are called Organic.

3. Carbon Cycle
The movement of carbon from the environment into living things and then back again is the Carbon Cycle.
You already know how carbon dioxide cycles between photosynthesis and cellular respiration.

4. Carbon Cycle
Carbon dioxide in the air enters into living things through photosynthesis.
Oxygen and glucose produced from photosynthesis are then used by plants and animals for cellular respiration.
Cellular respiration produces carbon dioxide to be released again.

5. Carbon Cycle
Keep in mind all living things have carbon in them, so when they die, decomposers help return that carbon to the environment and soil.

6. Carbon Cycle
Carbon in the environment is used to make coal, oil, and natural gas (fossil fuels).
Fossil fuels are burned in a process called Combustion.
Combustion releases carbon dioxide back into the air.

7. What is nitrogen?
Nitrogen is used to build proteins and DNA.

8. Nitrogen Cycle
The movement of nitrogen from the environment to living things and back again is the Nitrogen Cycle.
About 78% of the Earth’s atmosphere is nitrogen gas, however most organisms cannot use nitrogen when it’s in a gas form.

9. Nitrogen Cycle
Nitrogen fixation is when lightning or bacteria in the soil change nitrogen gas into a form that can be taken up by plant roots.

10. Nitrogen Cycle Animals eat the plants and therefore take in nitrogen.
When animals and plants die, decomposers help return the nitrogen to the soil.
Other bacteria then change the nitrogen in the soil back into a gas to be released back into the air.