The role of these bacteria in the nitrogen cycle is to convert free nitrogen into usable nitrogen.
Answer: Option D
Step-by-step explanation:
Bacteria plays a vital role in the conversion of free nitrogen into biologically available forms. The Nitrogen cycle is the biochemical cycle which involves bacteria. The Nitrogen fixing bacteria are either free living or symbiotic.
Nitrogen is found in different forms in the earth’s surface. 78% of the earth atmosphere contains Nitrogen gas. These gases are Inert and hence the bacteria act upon it to produce simpler form of usable Nitrogen through the Nitrogen cycle.