Answer & explanation:
1. In the nitrification process, the oxidation of ammonia (NH₃) occurs, converting it to nitrite and, subsequently, to nitrate. This process is performed by chemosynthetic bacteria (also known as nitrifying bacteria), that is, they use the energy released in nitrification to synthesize their organic substances.
2. Denitrification occurs when bacteria in the soil called denitrifiers use nitrates and turn them into nitrogen gas. Denitrification ensures the return of nitrogen to the atmosphere.
3. The fixation of atmospheric nitrogen occurs mainly with the help of bacteria. These bacteria form nodules in the cortical region of the roots of these plants, where they act by capturing atmospheric nitrogen and transforming it into ammonia (NH₃), which will be used by plants.
