Grasslands   Grasslands are found on every continent except Antarctica, and cover about 16 per cent of the Earth’s surface.  They develop where there is not enough precipitation to support forests, but enough to prevent deserts forming.

TLS Online TPP Program

#Id: 7297

#Unit 6. System Physiology – Plant

Phosphorylated PEPCase is catalytically more active and less sensitive to inhibition by malate than the nonphosphorylated form. PEPCase‐kinase catalyzes the phosphorylation of PEPCase

TLS Online TPP Program

#Id: 7298

#Unit 6. System Physiology – Plant

PPDK-RP make PPDK active removing phosphates of catalytic his/threo residues using ADP as phosphoryl donor, rather than ATP, and the phosphorolytic dephosphorylation of the (PPDK)−Thr−O−P with formation of pyrophosphate, rather than the hydrolysis employed by most protein

phosphatases.

TLS Online TPP Program

#Id: 7299

#Unit 6. System Physiology – Plant

TLS Online TPP Program

#Id: 7300

#Unit 6. System Physiology – Plant

Crassulacean acid metabolism (CAM). Temporal separation of CO2 uptake from photosynthetic reactions: CO2 uptake and fixation take place at night, and decarboxylation and refixation of the internally released CO2 occur during the day. The adaptive advantage of CAM is the reduction of water loss by transpiration, achieved by the stomatal opening during the night.

TLS Online TPP Program

#Id: 7301

#Unit 6. System Physiology – Plant

Typically, a CAM plant loses 50 to 100 g of water for every gram of CO2 gained, compared with values of 250 to 300 g and 400 to 500 g for C4 and C3 plants Thus, CAM plants have a competitive advantage in dry environments.

TLS Online TPP Program

#Id: 7302

#Unit 6. System Physiology – Plant

In CAM plants, formation of the C4 acids is both temporally and spatially separated. At night, CO2 is captured by PEP carboxylase in the cytosol, and the malate that forms from the oxaloacetate product is stored in the vacuole