Many proteins are regulated by the binding of GTP or GDP. Which form is the active state of the protein

GTP-bound form

Explanation:

Such a receptor may be associated with the GDP-regulated G-stimulant protein system. When the neurotransmitter binds to the receptor, the protein G-GDP complex is activated by separating its β subunit. When the ligand "sticks" to it, it releases GDP and allows GTP to bind. This form of the G protein that binds GTP, is the activated ("on") form of it. When it is "on" it releases signals into the cell. After a short period (seconds or less) the G protein hydrolyzes the GTP to GDP and itself "turns off".

for  example, forests have higher evapotranspiration than other ecosystems,  such  as grasslands, because of their deeper roots and greater leaf area. thus forests have a net moistening effect on the atmosphere and become a moisture source for downwind ecosystems.