Select the statement below that correctly represents a key aspect of nitrogenase activity and its regulation within the context of biological nitrogen fixation.
1
Nitrogenase enzymes are unique in requiring only ambient, atmospheric concentrations of oxygen O2 to catalyze the conversion of nitrogen N2 to ammonia NH3, without any additional energy input, making them highly efficient under aerobic conditions.
2
Nitrogenase enzymes are capable of fixing atmospheric nitrogen N2 into a usable form only under high temperatures, typically above 60°C, which facilitates the breaking of the strong triple bond of N2, thereby limiting nitrogen fixation to thermophilic organisms.
3
Nitrogenase activity is tightly regulated by the availability of fixed nitrogen sources, such as ammonium (NH4+), and is subject to feedback inhibition; when concentrations of fixed nitrogen are sufficient, the synthesis and activity of nitrogenase are down-regulated to conserve energy.
4
The nitrogenase enzyme complex directly converts atmospheric nitrogen N2 into nitrate NO3-, which is then assimilated by plants and other organisms, bypassing the need for intermediate forms such as ammonia NH3.
5
Question Not Attempted