Biology notes topic Nitrogen cycle of zoology.
Nitrogen Fixation: The cycle begins with nitrogen fixation, where atmospheric nitrogen gas (N2) is converted into a usable form by certain nitrogen-fixing bacteria or through human activities such as industrial processes or the Haber-Bosch process.
The following steps in nitrogen cycle are-
1. Ammonification: In this process, nitrogen-fixing bacteria convert the fixed nitrogen compounds into ammonium (NH4+), which can be used by plants.
2. Nitrification: Ammonium is further transformed into nitrite (NO2-) by nitrifying bacteria in a two-step process called nitrification. First, ammonium is converted into nitrite by ammonium-oxidizing bacteria (Nitrosomonas). Then, nitrite is converted into nitrate by nitrite-oxidizing bacteria (Nitrobacter).
3. Assimilation: Plants and other organisms take up nitrate and ammonium from the soil and use them to build proteins, nucleic acids, and other nitrogen-containing organic compounds.
4. Denitrification: Under anaerobic conditions, denitrifying bacteria convert nitrate back into nitrogen gas (N2), completing the cycle. This occurs in oxygen-limited environments like waterlogged soils or sediments.