1. T HE C ARBON AND O XYGEN C YCLE

2. A FEW PROCESSES THAT CONTROL THE CARBON AND OXYGEN CYCLE : Photosynthesis-respiration cycle Burial of organic carbon Weathering/erosion Decomposition Consumption

3. P HOTOSYNTHESIS -R ESPIRATION Conducted by plants Photosynthesis: water and CO 2 is taken up to create sugars and oxygen, with the help of solar energy 6 CO 2 + 12 H 2 O  C 6 H 12 O 6 + 6 H 2 O + 6 O 2 Respiration: energy is released by combining sugars and oxygen, and producing CO 2 and water C 6 H 12 O 6 + 6 H 2 O + 6 O 2  energy + 6CO 2 + 12 H 2 O

4. F IGURE 10-2

5. P HOTOSYNTHESIS - RESPIRATION No net exchange of CO 2 and O 2 with the atmosphere Plants need sugars to grow Increase in photosynthesis Sugars are used, not destroyed by CO 2 and water Reservoir of carbon in plant tissue O 2 is released in the atmosphere

6. T HREE FATES OF PHOTOSYNTHETICALLY PRODUCED CARBON 1) Consumption: animals employ respiration to gain energy from the sugars of the plants they eat They perform the photosynthesis-respiration cycle with plants CO 2 and O 2 pass through the atmospheric reservoir as they move from plants and animals Figure 10-3

7. T HREE FATES OF PHOTOSYNTHETICALLY PRODUCED CARBON 2) Decomposition: decomposers, such as bacteria and fungi, break down dead organic debris not consumed by animals Use respiration to break down tissue Figure 10-4

8. T HREE FATES OF PHOTOSYNTHETICALLY PRODUCED CARBON 3) Burial of plant debris: Some dead plant debris escapes the photosynthesis-respiration cycle through burial Reservoir of reduced carbon compounds Erosion exposes this carbon to the atmosphere Excess burial results in less CO 2 and more O 2 in the atmosphere Some deeply buried debris can become coal

9. C HEMICAL WEATHERING Uses CO 2 from the atmosphere to break down rocks Mountain building: extracts a large amount of CO 2 from the atmosphere Temperature: high temperature increases weathering Precipitation: helps weathering processes, and continental configuration pattern affects weathering Vegetation: more weathering processes in forests

10. E ROSION Erosion exposes carbon that has been buried The cycle of burial and erosion has been fairly stable, so the levels of CO 2 and O 2 in the atmosphere have been relatively stable

11. T ECTONIC ACTIVITY Volcanoes allow CO 2 to escape in the atmosphere where it can mix with water and then can perform chemical weathering processes on rocks Figure 10-11 b)