LIFESCI 1 Lecture Notes - Lecture 9: Keeling Curve, By2, Northern Hemisphere
Document Summary
Carbon cycle = atmospheric co2 varies through the years: add co2 by: 3) human activities (deforestation, fossil fuel burning: remove co2 by: 1) geologic removal (chemical weathering of rocks) Short term carbon cycling: photosynthesis = energy from sun into atp reduces co2 to sugar. Co2 is pulled out from environment, carbon carbohydrates, o2 = byproduct. 6co2 + 6h2o 6c6 h2o6 + 6o2. Photosynthetic organisms remove 190 billion metric tons of carbon (from. 700 billion metric tons of co2) every year: 60% land plants, 40% phytoplankton/seaweed. Removes about 25% of co2 from atmosphere annually. However, keeling curve says co2 levels are rising. High rates of photosynthesis would use all co2 in the world in a few years if not replenished. But ecosystems have been fueled by photosynthesis for billions of years w/o depleting co2: aerobic respiration = uses o2 to oxidize organic molecules to co2. Converts chemical energy in organic compounds to atp for cellular processes.
