ecosystems Flashcards
1
Q
what are the 4 steps in the nitrogen cycle
A
- nitrogen fixation
- ammonification
- nitrification
- denitrification
2
Q
what is nitrogen fixation
A
- nitrogen gas in the atmosphere is turned into ammonia by bacteria such as Rhizobium and Azotobacter
- this ammonia can be used by plants
3
Q
what is the bacteria Rhizobium and what does it do
A
- bacteria found inside root nodules (growth on the roots) of leguminous plants
- they form a relationship with the plants as they provide the plant with nitrogen compounds and the plant provides them with carbohydrates
4
Q
what is the process of ammonification
A
- when nitrogen compounds from dead organisms are turned into ammonia by decomposers
- these go on to form into ammonium ions
- animal waste also contains nitrogen compounds
5
Q
what is nitrification
A
- when ammonium ions in the soil are changed into nitrogen compounds that can be used by plants
6
Q
what nitrifying bacteria changes ammonium ions into nitrites
A
- nitrosomonas
7
Q
what does the bacteria nitrobacter do
A
- changes nitrites into nitrates
8
Q
what is denitrification
A
- when nitrates in the soil are converted into nitrogen gas by denitrifying bacteria
- use nitrates in the soil to carry out respiration and produce nitrogen gas
9
Q
what conditions does denitrification happen in
A
- anaerobic conditions, no oxygen e.g. waterlogged soils
