The Majority of Nitrogen in Soil and Marine Environments Is

Question

The majority of nitrogen in soil and marine environments is fixed by
A) free-living bacteria and archaea.
B) symbionts.
C) E. coli.
D) biofilm organisms.
E) UV light.

Accepted Answer

Free-living bacteria and archaea are responsible for the majority of nitrogen fixation in soil and marine environments. Symbiotic organisms, such as legumes with rhizobia, also contribute to nitrogen fixation but are not the primary source. E. coli and biofilm organisms may play a role in nitrogen cycling, but they do not fix nitrogen directly. UV light does not fix nitrogen.