Question

Give an account on nitrogen cycle and the process of biological nitrogen fixation

Answer 1

the series of processes by which nitrogen and its compounds are interconverted in the environment and in living organisms, including nitrogen fixation and decomposition.

some bacteria can convert N2 into ammonia by the process termed nitrogen fixation; these bacteria are either free-living or form symbiotic associations with plants or other organisms (e.g. termites, protozoa)
other bacteria bring about transformations of ammonia to nitrate, and of nitrate to N2 or other nitrogen gases
many bacteria and fungi degrade organic matter, releasing fixed nitrogen for reuse by other organisms.
All these processes contribute to the nitrogen cycle.