10/8/12

VII. Photorespiration- BAD. When plant cells close their stomata and the result is that CO2 can't get in, O2 can't get out, and O2 is "fixed" into the Calvin Cycle, not CO2. No Glucose, cell and eventually plant death is the result.
Plants that live in hot, dry conditions have developed C4 Photosynthesis- when CO2 is fixed onto a 4- Carbon compound. 2 types:
     A. C4 Plants- take in CO2 opportunistically into Mesophyll cells, where it is fixed onto a 4- Carbon compound. This 4- Carbon compound is moved into a bundle-sheath cell where it gives off its CO2 to the Calvin Cycle. Concentrates glucose only in these cells. Examples: sugarcane, corn
     B. CAM Plants-(cactus, pineapple) Open their stomata at night and store it in a C4 compound and then strip the CO2 off of it when needed and the CO2 enters the Calvin Cycle. All this happens in Mesophyll cells.