SME
Grade 9 Science · Problem type
The carbon cycle and energy
Use this for “How do photosynthesis and respiration move carbon between the air and living things?”
Explore
Carbon is stored in the air as CO₂, in living things, in dead matter, in the ocean and in fossil fuels.
Every arrow moves carbon from one store to another.
Assumptions
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Photosynthesis, 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂, stores the Sun’s energy in sugar.
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Cellular respiration runs the same equation backward, releasing that energy and the carbon dioxide.
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Carbon atoms are never used up: they cycle, while energy flows through once and leaves as heat.
Topic check
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