Question

With the help of a labelled diagram show
(a) Nitrogen cycle in nature
​(b) Describe briefly any two processes involved in the cycling of N₂ in the environment.

Answer 1

(a) Nitrogen-cycle is a biogeochemical cycle. It describes the transformation of atmospheric nitrogen to simpler molecules in soil and water that get converted to more complex molecules and eventually are converted back to the simple nitrogen molecule in the atmosphere. The given figure shows the nitrogen cycle.

(b) Two processes involved in the cycling of N₂ in the environment are -

1. Nitrogen fixation: N₂ NO₃ ⁻ or NH₄

It is the process wherein atmospheric nitrogen is converted into water-soluble nitrates. This step is performed by organisms like Rhizobium, Azotobacter and blue-green algae.

2. Nitrification: NH₃ NO₂ ⁻ NO₃ ⁻

It is the process in which ammonia is first converted into nitrites and then into nitrates. This step is performed by nitrifying bacteria like Nitrosomonas and Nitrobacter.