Carbon cycle
How carbon moves between the air, living things and the ground. Plants take in carbon dioxide and respiration, decay and burning return it.
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Analogy
A shared bank account where carbon is deposited and withdrawn.
In practice
Carbon in a tree can end up in the air when the wood is burned.
Practice
Interview questions
- Describe how carbon moves through the carbon cycle.
- Plants take carbon dioxide from the air by photosynthesis
- Carbon passes to animals when they eat
- Respiration and burning return carbon dioxide to the air
- Decomposers release carbon from dead material
Questions people ask
How does carbon dioxide get into the air?
Carbon dioxide enters the air through respiration by plants, animals and microorganisms. It is also released by decomposers and by burning fossil fuels and wood, called combustion. Photosynthesis takes it back out. When the two are balanced, the amount in the air stays steady.
What are fossil fuels?
Coal, oil and natural gas are fossil fuels. They formed over millions of years from the remains of dead plants and tiny sea creatures buried and squashed underground. Burning them releases carbon that had been locked away for a very long time, adding extra carbon dioxide to the air.