AP BIOLOGY

Detailed explanation-1: -nitrogen fixation, any natural or industrial process that causes free nitrogen (N2), which is a relatively inert gas plentiful in air, to combine chemically with other elements to form more-reactive nitrogen compounds such as ammonia, nitrates, or nitrites.

Detailed explanation-2: -Nitrogen gas is called “free” nitrogen, meaning it is not combined with other kinds of atoms. Most organisms can use nitrogen only once it has been “fixed, ” or combined with other elements to form nitrogen-containing compounds.

Detailed explanation-3: -The process of combining nitrogen with other elements in order to make usable compounds is called nitrogen fixation. Most nitrogen is transformed into usable nitrogen compounds by nitrogen-fixing bacteria. Some nitrogen-fixing bacteria live in special swelling on the roots of legume plants.

Detailed explanation-4: -In the atmosphere, nitrogen exists as a gas (N2), but in the soils it exists as nitrogen oxide, NO, and nitrogen dioxide, NO2, and when used as a fertilizer, can be found in other forms, such as ammonia, NH3, which can be processed even further into a different fertilizer, ammonium nitrate, or NH4NO3.