Question

For its activity nitrogenase requires

• A. High input of energy
• B. Light
• C. $M{n}^{2+}$
• D. Super oxygen radicals

Answer 1

The correct option is A High input of energy

Reduction of inert atmospheric nitrogen to ammonia by living organisms is called biological nitrogen-fixation. Only certain prokaryotic organisms (some bacteria and cyanobacteria) are capable of fixing $N_2$. Such microbes are called $N_2$-fixers. These $N_2$-fixing microbes contain an exclusive enzyme, Nitrogenase that is capable of reducing nitrogen. This enzyme is required to fix atmospheric nitrogen ($N\equiv N$). It is made up of Mo-Fe protein. For its activity, nitrogenase requires high input of energy. It catalyzes the conversion of atmospheric nitrogen to ammonia. The synthesis of ammonia requires very high input of energy. It requires 8 ATP for each $N{H}_3$ energy. The energy required is obtained from the respiration of the host cells.

The overall reaction involved in $N_2$-fixation is

$N_2+8e^{-}+8H^{+}+16ATP\to 2N{H}_3+H_2+16ADP+16P_i$