The carbon cycle
Carbon is an essential element for life on Earth and parts of each of the cells in our bodies are made from it. The carbon cycle shows how atoms of this element can exist within different compounds at different times.
Image caption, Stage one of the carbon cycle
Carbon enters the atmosphere as carbon dioxide from respiration and combustion.
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The The processes and events involved in recycling carbon in the environment. is easiest to understand in terms of its processes and the conversion of carbon that they undertake. The three key processes and their conversions are shown in the table below.
| Process | Carbon starts as | Carbon ends as |
| Photosynthesis | Carbon dioxide | Glucose |
| Respiration | Glucose | Carbon dioxide |
| Combustion (burning) | Fuel (eg methane or wood) | Carbon dioxide |
| Process | Photosynthesis |
|---|---|
| Carbon starts as | Carbon dioxide |
| Carbon ends as | Glucose |
| Process | Respiration |
|---|---|
| Carbon starts as | Glucose |
| Carbon ends as | Carbon dioxide |
| Process | Combustion (burning) |
|---|---|
| Carbon starts as | Fuel (eg methane or wood) |
| Carbon ends as | Carbon dioxide |
Learn more about the carbon cycle with Dr Alex Lathbridge.
Listen to the full series on 大象传媒 Sounds.
Explore what happens to carbon at each stage of the cycle and the different processes involved.