Nitrogen Cycle Flashcards
Define ‘atmospheric nitrogen’
N2: makes up 78% of Earth’s atmosphere. Component of protiens and nucleic acids.
Outline the steps involved in the nitrogen cycle
- Nitrogen fixation
- Nitrogen assimilation
- Ammonification
- Nitrification
- Dentrification
What is nitrogen fixation?
Any natural or industrial process which causes free nitrogen to combine chemically with other elements, creating more reactive nitrogen compounds (ammonia, nitrates, nitrites).
How does nitrogen enter the living world?
Through bacteria and other single-celled prokaryotes, which convert N2 into biologically usable forms, such as inorganic nitrogen compounds.
Ammonia: combines with hydrogen
Nitrates: combines with oxygen
What is nitrogen assimilation?
The formation of amino acids from inorganic nitrogen compounds in the environment.
What is ammonification?
Takes place due to the existence of decomposers. Converts organic nitrogen into organic ammonia or ammonium ions. Returns nitrogen to soil or water in a way that allows plants to take it up and pass it along the food chain.
What is dentrification?
Nitrogen is converted back into N2 (nitrogen gas) by bacteria. Nitrogenous compunds converted to ammonia NH3 by bacteria and wastes are converted into nitrates and nitrites. Nitrates made into N2 gas by detrfying prokaryotes.
Discuss nitrogen as a limiting nutrient
Nitrogen is often the limiting nutrient, or the nutrient in shortest supply, thus limiting the growth of organisms/populations.
How do you know if a nutrient is limiting?
- If it is limiting, adding more of it will increase growth.
- If a non limiting nutrient is added, it won’t have an effect.
What is eutrophication?
Excessive plant and algal growth due to increased availability limiting growth factors needed for photosynthesis.
Explain the process of eutrophication
Fertisilers containing nitrogen and phosphorous is washed into lakes, streams and rivers, with the excess nutrients causing overgrowth of algae and other microorganisms. Reduces oxygen availability in water, causing the death of other organisms.
