Study Notes
The nitrogen cycle is a crucial process in ecosystems, involving the conversion of nitrogen into various chemical forms.
- Nitrogen Fixation — conversion of atmospheric nitrogen into ammonia by bacteria. Example: Rhizobium bacteria in legume root nodules.
- Nitrification — conversion of ammonia into nitrites and then nitrates by bacteria. Example: Nitrosomonas and Nitrobacter bacteria.
- Assimilation — absorption of nitrates by plants to form proteins. Example: Plants using nitrates to grow and develop.
- Ammonification — conversion of organic nitrogen into ammonia by decomposers. Example: Decomposing plant and animal matter.
- Denitrification — conversion of nitrates back into nitrogen gas by bacteria. Example: Pseudomonas bacteria in waterlogged soils.
Exam Tips
Key Definitions to Remember
- Nitrogen Fixation
- Nitrification
- Assimilation
- Ammonification
- Denitrification
Common Confusions
- Confusing nitrification with nitrogen fixation
- Misunderstanding the role of bacteria in the nitrogen cycle
Typical Exam Questions
- What is nitrogen fixation? Conversion of atmospheric nitrogen into ammonia by bacteria.
- How does nitrification occur? Ammonia is converted into nitrites and then nitrates by bacteria.
- What role do plants play in the nitrogen cycle? They absorb nitrates to form proteins.
What Examiners Usually Test
- Understanding of the different stages of the nitrogen cycle
- The role of bacteria in each stage
- The importance of the nitrogen cycle in ecosystems