1. Understanding: Skills: 4.3 Carbon cycle
- Construct a diagram of the carbon cycle
Understanding:
Autotrophs convert carbon dioxide into carbohydrates and other carbon compounds
In aquatic habitats carbon dioxide is present as a dissolved gas and hydrogen carbonate ions
Carbon dioxide diffuses from atmosphere or water in autotrophs
Carbon dioxide is produced by respiration and diffuses out of organisms in water or atmosphere
Methane is produced from organic matter in anaerobic conditions by methanogenic archaeans and some diffuses into the atmosphere
Methane is oxidised to carbon dioxide and water in the atmosphere
Peat forms when organic matter is not fully decomposed because of anaerobic conditions in water logged soils.
Partially decomposed organic matter from past geological eras was converted into oil and gas in porous rocks or into coal
Carbon dioxide is produced by the combustion of biomass and fozzilised organic matter
Animals such as reef building corals and molluscs have hard parts that are composed of calcium carbonate and can become fossilised in limestone
Nature of science:
Making accurate, quantitative measurements: it is important to obtain reliable data on the concentration of carbon dioxide and methane in the atmosphere
Applications
Estimation of carbon flues due to processes in the carbon cycle
Analysis of data from atmosphere monitoring stations showing annual fluctuations

8. C Cycle WB

9. The carbon cycle Terms: Pool = reserve of the element
Carbon dioxide in atmosphere
Biomass of producers in ecosystem
Flux = transfer of the element from one pool to another
Absorption of carbon dioxide from the atmosphere by plants, contributing to plant biomass through photosynthesis

10. Carbon fluxes Process Flux/gigatonnes a year Photosynthesis 120
Cell respiration
119.6
Ocean uptake
92.8
Ocean loss 90
Deforestation and land use changes
1.6
Burial in marine sediments
0.2
Combustion of fossil fuels
6.4

11. Use page 220 - 225 to add details to your carbon cycle
Add methanogenesis and oxidation of methane to your cycle
221
Add peat formation to your cycle
224/225
Use page to add details to your carbon cycle

12. Carbon Fixation
Autotrophs absorb carbon dioxide from the atmosphere Convert into carbon compounds they require (glucose, AA, Lipids)

13. Carbon Dioxide
Carbon dioxide is soluble in water. Either dissolves in water, or combine with water to form carbonic acid. Carbonic acid then splits to form hydrogen and hydrogen carbonate ions. Decrease in pH (problems?) Both carbon dioxide and hydrogen carbonate ions absorbed by autotrophs in the water by diffusion.

14. Methanogenesis
Methanogenic archaeans (single celled like bacteria) Methane (CH4) is produced in anaerobic conditions as a waste product.
Mud in beds of lakes
Swamps (or other areas where soil is waterlogged)
Guts of cattle and sheep
Landfill sites.

15. Methane in the atmosphere
Methane is oxidised to carbon dioxide and water in the atmosphere. CH4 + O2 H2O + CO2
*methane is a greenhouse gas though!

16. Peat formation
Waterlogged environments (water unable to drain out = anaerobic conditions) Saprotrophs cannot survive here - no oxygen – not all dead matter is broken down Large quantities of partially decomposed matter accumulates in ecosystem – compresses to form peat.
Peat is also used as a fuel which releases carbon dioxide back into the atmosphere

17. Fossilisation
Incomplete decomposition of organic matter which has been buried, compressed and heated underground from past geological eras.
Most commonly under the sea – anaerobic conditions
Forms:
Crude oil
Natural gas
Coal

18. Limestone
Some animals have hard body parts composed of calcium carbonate
Mollusc shells
Hard corals
Soft parts decompose. Hard calcium carbonate deposited on sea bed – creating limestone rock
10% of all sedimentary rock is limestone
12% mass of calcium carbonate is carbon
Huge amounts of carbon locked up in limestone rock on earth

19. Building a carbon cycle
Notes for the team leader:
You need to make a carbon cycle with the materials provided (big whiteboards, small whiteboards, rulers/string, arrow heads, pens etc)
Each pool and fluxes needs to be labelled and explained:
Carbon fixation in photosynthesis
Carbon dioxide in solution in the ocean
Aquatic autotrophs absorbing carbon dioxide
Respiration
Methanogenesis and oxidation of methane
Peat formation
Fossilisation
Limestone as a pool of carbon
Combustion of fossil fuels (peat is also used as a fuel)
Allocate jobs to your team
25 minutes Go

20. Building a carbon cycle
Notes for the team leader:
You need to make a carbon cycle with the materials provided (big whiteboards, small whiteboards, rulers/string, arrow heads, pens etc)
Each pool and fluxes needs to be labelled and explained:
Carbon fixation in photosynthesis
Carbon dioxide in solution in the ocean
Aquatic autotrophs absorbing carbon dioxide
Respiration
Methanogenesis and oxidation of methane
Peat formation
Fossilisation
Limestone as a pool of carbon
Combustion of fossil fuels (peat is also used as a fuel)
Allocate jobs to your team
25 minutes Go

21. Speaking and listening
Get into pairs. One person in the pair faces the board (speaker) The other person faces away so they cannot see the board (listener) Speaker describes what they see on the board to the listener – with neither turning around. We will swap to complete the second half of the diagram.