Question

Explain Nitrogen cycle.

Answer 1

Nitrogen cycle:

1. Nitrogen gas makes up 78% of the atmosphere and nitrogen is also a part of many molecules essential to life like proteins, nucleic acids (DNA and RNA), and some vitamins.

Fixation of nitrogen:

1. Nitrogen is converted to nitrates by nitrogen-fixing bacteria.
2. Nitrogen-fixing bacteria are found in the roots of legumes in special structures called root nodules.
3. Other than these bacteria, the nitrogen molecule is converted to nitrates and nitrites by a physical process.
4. During lightning, the high temperatures and pressures created in the air convert nitrogen into oxides of nitrogen.
5. These oxides dissolve in water to give nitric and nitrous acids and fall on land along with rain.
6. These are then utilized by various life forms.
7. Plants generally take up nitrates and nitrites and convert them into amino acids which are used to make proteins.
8. These proteins and other complex compounds are subsequently consumed by animals.
9. Once the animal or the plant dies, other bacteria in the soil convert the various compounds of nitrogen back into nitrates and nitrites.
10. A different type of bacteria converts nitrates and nitrites into elemental nitrogen.
11. Thus, there is a nitrogen cycle in nature in which nitrogen passes from its elemental form in the atmosphere into simple molecules in the soil and water, which get converted to more complex molecules in living beings and back again to the simple nitrogen molecule in the atmosphere.​