Essential Idea
Continued availability of carbon in ecosystems depends on carbon cycling.
Understandings
Autotrophs convert carbon dioxide into carbohydrates and other carbon compounds.
In aquatic ecosystems carbon is present as dissolved carbon dioxide and hydrogen carbonate ions.
Carbon dioxide diffuses from the atmosphere or water into autotrophs.
Carbon dioxide is produced by respiration and diffuses out of organisms into water or the atmosphere.
Methane is produced from organic matter in anaerobic conditions by methanogenic archaeans and some diffuses into the atmosphere or accumulates in the ground.
Methane is oxidized to carbon dioxide and water in the atmosphere.
Peat forms when organic matter is not fully decomposed because of acidic and/or anaerobic conditions in waterlogged soils.
Partially decomposed organic matter from past geological eras was converted either into coal or into oil and gas that accumulate in porous rocks.
Carbon dioxide is produced by the combustion of biomass and fossilized organic matter.
Animals such as reef-building corals and mollusca have hard parts that are composed of calcium carbonate and can become fossilized in limestone.
Applications
Estimation of carbon fluxes due to processes in the carbon cycle.
Analysis of data from air monitoring stations to explain annual fluctuations.
Skills
Construct a diagram of the carbon cycle (VIDEO).
Guidance
Carbon fluxes should be measured in gigatonnes.
Key Vocabulary
Carbon compound
Carbon dioxide
Hydrogen carbonate
Methane
Calcium carbonate
Carbon flux
Carbon cycle
Methanogen
Oxidize
Peat
Porous
Combustion
Biomass
Fossil
Textbook Reading and/or Activities
Click HERE for a pdf of chapter 4.
Pages 202-214
Challenge Yourself (p.212)
Worked Example (p.212-213)
Exercises (p.214)
Notes
A detailed set of notes, prepared by Bob Smullen, examining U1-U10, A1-A2 and S1.
Another detailed set of notes, prepared by Stephen Taylor, that includes material on the whole of Topic 4. Worth checking out.
A detailed set of notes, created by Chris Paine, examining all of the IB learning expectations.
A series of questions, prepared by Jacob Cedarbaum, to help you prepare for the relevant sections of the IB Exam. This is VERY GOOD practice.
A series of questions, prepared by Bob Smullen, to help check your understanding of both Topic 4 and Option C based on Ecology. This is VERY GOOD practice.
A series of questions, prepared by Jacob Cedarbaum, to help check your understanding of the IB learning expectations for all of Topic 4. Check your work when you're done HERE. This is VERY GOOD practice.
Learning Activities
This activity, prepared by Annenberg Learner, will help you better understand the changes and impacts of carbon in our environment (A1).
Supplemental Reading
This video outlines the water and carbon cycles, where are arguably the most important for living organisms.
This video outlines the process by which fossil fuels are produced through the decomposition of organic matter.
Should Watch Videos
This video examines the various nutrient cycles that exist on Earth. It is not necessary to understand the phosphorus or sulfur cycles.
This video describes the process by which carbon cycles through the various components of the environment.
Must Watch Videos