This topic summary covers Knowledge Organiser within Carbon Cycle for GCSE Biology. Topic 3: Carbon Cycle It is section 10 of 11 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 10 of 11
Practice
15 questions
Recall
20 flashcards
Knowledge Organiser
Key Terms
- Carbon cycle: Continuous movement of carbon through living and non-living systems
- Carbon sink: Reservoir that absorbs more carbon than it releases
- Carbon source: Releases more carbon than it absorbs
- Fossil fuels: Long-term carbon stores (coal, oil, gas)
- Combustion: Burning — releases CO2 rapidly
- Decomposition: Breakdown by bacteria/fungi — releases CO2
Processes Summary
- CO2 removed from atmosphere: photosynthesis only
- CO2 returned to atmosphere: respiration, combustion, decomposition
- Plants both absorb (photosynthesis) AND release (respiration) CO2
- Fossil fuels take millions of years to form; seconds to burn
- Peat bogs: oxygen-poor = slow decomposition = carbon storage
Human Impacts
- Burning fossil fuels: releases ancient stored carbon as CO2
- Deforestation: reduces photosynthesis + releases carbon via combustion/decomposition
- Draining peat bogs: enables aerobic decomposition, releasing stored CO2
- All increase atmospheric CO2, enhancing greenhouse effect