IGCSE Biology glossary
Nitrification
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Definition
The conversion of ammonium compounds in the soil into nitrites and then into nitrates by nitrifying bacteria. This is an aerobic process and is important because plants can absorb nitrogen in the form of nitrate ions through their roots.
What to include in an exam answer
Nitrifying bacteria are aerobic (need oxygen). They convert ammonium ions to nitrites, then nitrites to nitrates. Well-aerated soils promote nitrification, which is why farmers plough their fields.
Example in context
Describe the role of nitrifying bacteria in the nitrogen cycle (2 marks): Nitrifying bacteria convert ammonium compounds into nitrites and then into nitrates. Nitrates are the form of nitrogen that plants can absorb through their roots.
Related syllabus topic
Organisms & their environment