The Nitrogen Cycle + Mycorrhizae Flashcards
Why do organisms need nitrogen?
To make complex molecules such as bases, amino acids, nucleotides etc
How do plants take up nutrients from the soil?
Active transport
How is nitrogen passed from plants to animals?
Animals consume plants.
Define ammonification.
Production of ammonia from nitrogen containing compounds.
How do saprobionts return ammonium ions back to the soil?
They feed on faeces and dead organisms, returning them to the soil.
Name the process where ammonium ions convert to nitrite and then nitrate ions.
Nitrification
When ammonium ions are converted to nitrite, then to nitrate ions, what type of reaction occurs?
Oxidation, loss of hydrogen.
Give the general name of the organisms that allow nitrification to happen.
Nitrifying bacteria
Define nitrogen fixation.
Nitrogen gas converted to nitrogen containing compounds.
Name 2 types of nitrifying bacteria.
Free living nitrogen fixing bacteria
Mutualistic nitrogen fixing bacteria
What do free living nitrogen fixing bacteria do to nitrogen?
Why do they do this?
Reduce N to NH3 so amino acids can be made.
What happens when free living nitrogen fixing bacteria die?
Nitrogen rich compounds are released
Where do mutualistic nitrogen fixing bacteria live?
How is the bacteria able to survive?
What does the plant get in return for aiding the bacteria’s survival?
They live in nodules in plant roots.
The plant supplies the bacteria with carbohydrates for food.
In return, the bacteria supply the plant with amino acids.
When soils become waterlogged, why do the type of bacteria present change?
O2 concentration is lower, therefore the number of anaerobic bacteria increase
What do anaerobic denitrifying bacteria do?
Why is this bad?
Convert nitrates back to nitrogen
This reduces the amount nitrates in the soil meaning less nitrogen containing compounds can be produced.
