Lesson focus: Where does carbon go when a plant grows or a fuel burns?
Trace carbon between reservoirs using named processes.
Build on earlier learning
Chemical formulae and balancingUse conservation of atoms to track carbon through changes.
Practical
Tracking carbon through the cycle
- Place arrow cards for photosynthesis, respiration, decomposition and combustion between carbon stores.
- Decide the direction of each transfer.
- Identify which process removes carbon dioxide from the air.
Record: A completed carbon-cycle diagram.
The carbon cycle
Carbon atoms are recycled between the air, living things and the ground. Step through each process.
Step 1 of 9
You will be successful when you can…
- Identify carbon stores.
- Name processes on arrows.
- Trace a carbon atom through organisms.
- Explain redistribution by combustion.
Words that carry the science
- carbon store
- Reservoir holding carbon for a period of time.
- photosynthesis
- Process transferring carbon dioxide carbon into organic molecules.
- respiration
- Cell process releasing energy and often returning carbon dioxide.
- decomposition
- Breakdown of dead material, involving organisms and respiration.
- combustion
- Reaction with oxygen that releases energy and often carbon dioxide.
Track conserved carbon atoms between named stores
01Processes move carbon
photosynthesisThe reaction in which plants use light energy, absorbed by chlorophyll, to turn carbon dioxide and water into glucose and oxygen. transfers carbon from atmospheric carbon dioxide into plant biomass. Feeding transfers organic carbon between organisms.
02Carbon returns and becomes stored
respirationA chemical reaction in every living cell that releases energy from glucose; it is not the same as breathing. and decompositionWhen dead plants and animals are broken down by tiny living things such as bacteria and fungi. return carbon dioxide. Carbon also enters soils, oceans, sediments, carbonate rocks and fossil fuels over different timescales.
03Combustion redistributes atoms
combustionBurning: when a fuel reacts with oxygen and gives out heat and light. fossil fuel moves long-stored carbon into the atmosphere. Carbon atoms are conserved, but the amount in each store changes.
Trace one carbon atom
Follow carbon from air to grass to cow and back to air.
- Photosynthesis fixes carbon dioxide into organic molecules in grass.
- Feeding transfers the molecule or its carbon to the cow.
- Respiration oxidises some organic carbon.
- Carbon dioxide returns to air; other carbon may enter waste or tissue first.
How to make the reasoning visible: The atom changes molecular form and store but is not created or destroyed.
Carbon transfer map
Every arrow needs a process and a direction.
| From | Process | To | Carbon form/example |
|---|---|---|---|
| Atmosphere | Photosynthesis | Plant | Organic molecules |
| Plant | Feeding | Animal | Food molecules |
| Organism | Respiration | Atmosphere | Carbon dioxide |
| Dead matter | Decomposition | Soil/atmosphere | Organic carbon/CO₂ |
| Fossil fuel | Combustion | Atmosphere | Carbon dioxide |
Which process removes carbon dioxide from air?
Why does combustion increase atmospheric carbon without creating atoms?
Use the map. How does carbon get from a plant into an animal?
Check your understanding
Answer from memory, then check against the suggested answer.
What is carbon store?
What is photosynthesis?
What is respiration?
Name one process that adds carbon dioxide to the air.
Name the process that takes carbon dioxide out of the air.
Trace carbon from a leaf into soil and atmosphere.
Why can atmospheric carbon rise even if total Earth-system carbon is conserved?
Explain how carbon in a tree can end up back in the air.
Exam Question Practice
Exam Question Practice
Mark points shown after marking
Name one process that removes carbon dioxide from air and two that return it, then explain conservation.
(4)Total for this question: 4 marks
Command word: Name processes, not only stores, and keep carbon matter separate from energy.