Understanding the Carbon Cycle in Nature

1. The Carbon Cycle

2. Photosynthesis • Plants and other photosynthetic organisms (some bacteria and protists) capture energy from sunlight and use it to make sugars-glucose (organic molecules), which they can then use in their cells. • Plants use sunlight, water, and CO2 (carbon dioxide) to produce sugars (glucose) and O2 (oxygen gas) • PHOTOSYNTHESIS EQUATION • Sunlight energy + 6H2O + 6CO2 C6H12O6 + 6O2

3. Cellular Respiration (Aerobic) • Glucose is one product of photosynthesis • Organisms take in sugars (glucose) made by photosynthetic organisms and break it down to release energy (energy is released when bonds of glucose are broken); producers make their own sugars (glucose) during photosynthesis and break it down to release energy • Aerobic Respiration uses sugars (glucose) and O2 (oxygen gas) to produce water, CO2 (carbon dioxide), and cellular energy (called ATP) • CELL RESPIRATION EQUATION (AEROBIC) • C6H12O6 + 6O2  6H2O + 6CO2 + ATP (energy)

4. Carbon Cycle • Photosynthesisand Respiration are basis for the biological carbon cycle (inverses of one another) • Photosynthesis takes in CO2and H2O and releases O2 to the atmosphere and makes sugars (glucose= C6H12O6) in the plant • Respiration takes in O2 and sugars (glucose= C6H12O6) and releases CO2 and H2O to the atmosphere (All organisms use some form of respiration) • These both occur in terrestrial and aquatic ecosystems

5. Carbon Cycle • Decomposition by bacteria returns carbon compounds to the soil from dead organisms • Erosion and volcanic activity release CO2 to the atmosphere and oceans • Sedimentary rock contains large amounts of carbon compounds which can be released when rock is broken down • Human activity increases CO2 levels in the atmosphere • Burning of fossil fuels increases CO2 in the atmosphere • Deforestation increases CO2 (since plants would normally take in the CO2) • CO2 production by respiration and CO2 use by photosynthesis would be balanced if not for human activity

6. Diagram