The role of bacteria in the nitrogen cycle: saprobiotic nutrition, ammonification, nitrification, nitrogen fixation and denitrification
Bacteria drive the nitrogen cycle by converting nitrogen compounds between different forms. Each type of bacterium performs a specific job — from breaking down dead matter to fixing atmospheric nitrogen gas into usable compounds.
Formula
N₂ → NH₄⁺ (fixation) → NO₂⁻ → NO₃⁻ (nitrification) → N₂ (denitrification)
Real World
Rhizobium bacteria in root nodules of clover plants fix atmospheric N₂ into NH₄⁺, which is why farmers rotate crops with legumes to naturally restore soil nitrogen without synthetic fertiliser.
Exam Focus
Learn the five processes and their directions — examiners frequently ask you to distinguish ammonification from nitrification using correct ion names.
Evaluation Scaffold
A four-step framework for high-quality evaluation. Use this for 'assess', 'evaluate', and 'to what extent' questions.
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