C3 Pathway These temperate or cool-season plants flourish at an optimum temperature of 65-75℉, soil temperature 40-45℉ Less efficient at higher temperatures Primary product is 3-phosphoglyceric acid or 3-carbon acid It takes place in three steps – carboxylation, reduction and regeneration C4 Pathway Plants in the tropical region are observed following this pathway Two-step process where Oxaloacetic acid is a 4-carbon compound that is produced Takes place in bundle sheath and mesophyll cells found in the chloroplast These can either be annual or perennial and ideal temperature for their growth is 90-95℉ Examples are Indiana grass, big bluestem, Bermudagrass, CAM Plants In this type of photosynthesis, entities absorb energy during daytime from sunlight using this energy at the night aby gathering carbon dioxide This adaptation is observed during the time of drought, allowing gaseous exchange during the night when the temperature of the air is cooler along with loss of water vapour Examples are plants such as euphorbias and Cactus. Irregular water supply has caused bromeliads and orchids to adapt to this pathway Difference Between C3, C4 and CAM pathway Listed below are some significant differences C3 C4 CAM What it means This pathway is observed in C3 plants wherein the primary product from sunlight post carbongrasping is 3phosphoglyceric acid to produce energy Sunlight is converted into oxaloacetic acid by some plants prior to C3 cycle which is further converted into energy. The plants are known as C4 plants. It is the C4 pathway Cells included Plants store solar energy post which they convert into energy in the night, such plants are CAM plants and the pathway is referred to as CAM pathway Mesophyll cells Bundle sheath cells, Mesophyll cells Mesophyll cells in C3 and C4, both Observed in All plants carrying out photosynthesis Tropical plants Semi-dry climatic conditions Plant types that use this cycle Hydrophytic, Mesophytic, Xerophytic plants Mesophytic plants Xerophytic plants Photorespiration process Observed in higher rates Not seen as much Observed in the noon time First-stable product produced 3-phosphoglycerate Daytime – 3-phosphoglycerate Night time – Oxaloacetate Oxaloacetate Number of molecules of NADPH and ATP required to produce glucose NADPH – 12 ATP – 18 NADPH – 12 ATP – 30 NADPH – 12 ATP – 39 The ideal photosynthetic temperature 15-25 degree celsius 30-40 degree celsius Greater than 40-degree celsius Calvin cycle functional Not accompanied with any other cycle Accompanied along with C4 pathway C4 pathway and C3 Example Beans, Spinach, Sunflower, Rice, Cotton Maize, Sorghum, Sugarcane Orchids, Cacti, euphorbias Carboxylating enzyme In C3, RuBP carboxylase PEP carboxylase – mesophyll RuBP carboxylase – bundle RuBP carboxylase – day time PEP carboxylase – night time sheath Ratio – Co2:ATP: NADPH2 The ratio is 1:3:2 The ratio is 1:5:2 The ratio is 1:6:5:2 Kranz Anatomy Not present Present Not present Initial CO2 receptor Ribulose-1, 5-biphosphate Phosphoenolpyruvate Phosphoenolpyruvate
