Carbon cycling

Topic 4.3

Essential idea: Continued availability of carbon in ecosystems depends on carbon cycling.


4.3.U1 Autotrophs convert carbon dioxide into carbohydrates and other carbon compounds

Autotrophs use carbon dioxide

4.3.U2 In aquatic ecosystems carbon is present has dissolved carbon dioxide and hydrogen carbonate ions

Carbon dioxide in aquatic ecosystems

4.3.U3 Carbon dioxide diffuses from the atmosphere or water into autotrophs

Carbon dioxide diffusion into leaf

4.3.U4 Carbon dioxide is produced by respiration and diffuses out of organisms into water or the atmosphere

Carbon dioxide production in cellular respiration

4.3.U5 Methane is produced from organic matter in anaerobic conditions by methanogenic archaeans and some diffuses                      into the atmosphere or accumulates in the ground

Production of methane by methogenic archaeans

4.3.U6 Methane is oxidized to carbon dioxide and water in the atmosphere

Methane oxidized to carbon dioxide in the atmosphere

4.3.U7 Peat forms when organic matter is not fully decomposed because of acidic and/or anaerobic conditions in waterlogged soils

Formation of peat

4.3.U8 Partially decomposed organic matter from past geological areas was converted either into cool or into oil and gas                      that accumulate in porous rocks

Formation of coal, oil and gas

4.3.U9 Carbon dioxide is produced by combustion of biomass and fossilized organic matter

Combustion of coal, oil and gas

4.3.U10 Animals such as reef-building corals and mollusca a have hard parts that are composed of calcium carbonate                      and become fossilized in limestone

Corals, mollusca and limestone


4.3.A1 Estimation of carbon fluxes due to the processes in the carbon cycle

Estimation of carbon fluxes

4.3.A2 Analysis from air monitoring stations to explain annual fluctuations

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Analysis of carbon dioxide monitoring data from different stations
Show explanation Explanation of annual fluctuations | Hide explanation Explanation of annual fluctuations
Annual fluctuations in CO2 explained


4.3.S1 Construction of a diagram of the carbon cycle

Diagram of carbon cycle
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