Differences between C3, C4, and CAM plants

C3, C4, an CAM plants all have light dependent reactions and the Calvin Benson cycle but the differences between C3 and C4, is that C3 convets CO2 and ribulose biphosphate into 3-phosphoglycerate by using the reaction 6 CO2 + 6RuBP ---> 12 3GP. C4 uses the PEP carboxylase in the uptake of CO2, allowing CO2 to be taken into the plant quicker and then delivers the CO2 to RUBISCO for photosynthesis. In C3 the photosynthesis takes place in inner cells while C3 photosynthesis takes place throughout the leaf. C3 is more efficient then C4 and CAM because it requires fewer enzymes and no specialized anatomy but C4 photosynthesizes faster then C3 plants because the C02 is delivered directly to RUBISCO, preventing it to grab oxygen and undergo photorespiration. C4 also has better water use efficiency because PEP Carboxylase brings in CO2 faster so it does not need to keep its stomata open as much as C3 or CAM plants. This gives C4 the advantage of losing less water by transpiration. CAM stores its C02 in acid form before photosynthesis during the night. During the day, the acid is broken down and the CO2 is released to RUBISCO for photosynthesis. CAM keeps its stomata open during the night and keeps it closed during the day. CAM plants also have the ability to become idle in order for them to survive dry environments. When CAM idle, they closed their stomata night and day. During this time they use oxygen for respiration and use CO2 from respiration for photosynthesis.

http://wc.pima.edu/Bfiero/tucsonecology/plants/plants_photosynthesis.htm
http://tables-evo-sci.blogspot.com/2007/11/comparison-of-c-3-c-4-cam-plants.html