5.3.3Unit 5: Respiration, Internal Environment, Coordination and Gene Technology
Carbon Cycle and Environmental Management — IAL Edexcel Linear Revision Notes & Topical Questions
5 min read 5 parts Lesson 27 of 36 Unit quiz
Section 1 of 5Carbon Pools
Stores of carbon are called pools, and the processes that move carbon between them are called fluxes.
Atmosphere
- Carbon is present in the air as carbon dioxide, which is the form taken up by producers.
Living biomass
- Carbon is held in carbohydrates, proteins, lipids and nucleic acids in the bodies of living organisms.
Oceans
- Carbon is dissolved as carbon dioxide and hydrogencarbonate ions, and is also built into calcium carbonate shells and skeletons.
Long-term stores
- Peat and fossil fuels formed from partly decayed organisms and hold carbon for very long periods.
Section 2 of 5Moving Carbon Between Pools
1
Producers remove carbon dioxide from the air by photosynthesis and build the carbon into carbohydrates and other molecules.
2
Carbon passes to consumers when animals feed on plants or on other animals and digest the molecules.
3
Plants, animals and microorganisms return carbon dioxide to the air through respiration.
4
Decomposers such as bacteria and fungi break down dead material and release carbon dioxide as they respire.
5
Combustion of wood, peat and fossil fuels converts stored carbon to carbon dioxide and returns it to the atmosphere.
Section 3 of 5Reducing Carbon Entering the Air
Reducing Carbon Entering the Air
Burn less fossil fuel
- Using less coal, oil and gas for transport and power cuts the main extra flux of carbon into the atmosphere.
Burn less biomass
- Reducing the burning of wood and other plant material keeps its carbon in the stored pool.
Protect carbon pools
- Leaving peat bogs and soils undisturbed stops them from releasing stored carbon as carbon dioxide.
Why it works
- Each of these actions lowers a transfer into the atmosphere, so the atmospheric concentration rises more slowly.
Section 4 of 5Increasing Carbon Removal
Plant trees
- Planting trees increases photosynthesis, which transfers carbon dioxide from the air into plant biomass.
Stop deforestation
- Keeping existing forests means that their biomass remains a store and their photosynthesis continues.
Time lag
- Trees take many years to grow, so planting offsets emissions only gradually and cannot replace emission cuts.
Combined approach
- The most effective strategy reduces emissions and increases removal together.
Section 5 of 5Exam Checklist & Tips
5.3.3 – Key Points for the Exam
- Carbon pool A store of carbon, such as the atmosphere, biomass, oceans or fossil fuels.
- Flux A transfer of carbon from one pool to another, such as photosynthesis or respiration.
- Decomposer A bacterium or fungus that breaks down dead organic matter and releases carbon dioxide.
- Combustion Burning, which releases carbon dioxide from stored fuels.
Common Mistakes
- Saying plants only remove carbon;
- they also release carbon dioxide by respiration, though net uptake is greater while they grow.
- Stating that carbon dioxide is the only form of carbon in the cycle;
- oceans hold hydrogencarbonate and carbonates.
- Forgetting that decomposers return carbon to the air, so dead material is not a permanent store.
- Thinking tree planting alone can solve the problem, which ignores the time trees take to mature.
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