Answer:
Nitrogen is required by all living organisms.
Explanation:
All organisms from bacteria, to plants, and even humans obtain our nitrogen, either directly or indirectly, via the nitrogen cycle.
The nitrogen cycle describes how nitrogen is converted from N₂, to ammonia/ammonium, which is then converted to nitrates and nitrites, and can even be <u>denitrified</u> back into atmospheric nitrogen.
There are many reasons that the nitrogen cycle is needed. The most important reason is that humans and plants cannot assimilate atmospheric nitrogen, they can only be absorbed in the form of <u>nitrogen containing compounds</u> (nitrates and nitrites). Once it has been assimilated by plants (where humans then consume nitrogen by eating plants), the nitrogen in the compounds is used to build up many other compounds in our bodies, such as amino acids, proteins, and even DNA and RNA contains nitrogen based compounds.