C3 Photosynthesis
C3 photosynthesis is a type of photosynthesis used by plants that use the Calvin cycle to fix carbon dioxide from the air. In this process, the first product of carbon dioxide assimilation is 3-phosphoglycerate, an organic compound with three carbon atoms.
The Calvin cycle produces a three-carbon compound from C3 photosynthesis, whereas C4 photosynthesis produces an intermediate four-carbon compound that splits into a three-carbon compound for the Calvin cycle.
C4 Photosynthesis
C4 photosynthesis is a series of anatomical and biochemical changes that increase the concentration of carbon dioxide (CO2) around the carboxylating enzyme Rubisco.
This increases the efficiency of photosynthesis in conditions that promote high rates of photorespiration.
CAM Photosynthesis
Crassulacean acid metabolism (CAM) photosynthesis is a carbon fixation pathway that allows plants to photosynthesize during the day and exchange gases at night.
CAM photosynthesis is an adaptation to arid conditions. It reduces photorespiration, improves water-use efficiency, and helps plants adapt to hotter and drier climates.
CAM photosynthesis is a CO2-concentrating mechanism that uses a C4 cycle. In CAM plants, stomata open at night when conditions are cool and humid. The following steps occur:
CO2 diffuses into the leaf
CO2 combines with PEP to form malate
Malate is stored in large central vacuoles until daytime
CAM photosynthesis is an elaboration of the standard C3 photosynthetic pathway. CAM photosynthesis can be both inducible and constitutive. It is known in 33 families with an estimated 15 to 20,000 species.
Examples of CAM plants include: Cacti, Pineapple.