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3 global cycles
- 1) nitrogen cycle
- 2) Carbon cycle
- 3) Sulfur cycle
which 4 biological molecules use nitrogen
- 1)amino acids
- 2)nucleic acids
- 3) enzymes
- 4) vitamins
_____ ____ converts organic nitrogen gas into organic nitrogen.
____ converts organic nitrogen into ammonia
% of the nitrogen gas into atmosphere is
____ converts ammonia into nitrate
____ converts nitrates into nitrogen gas
4 steps in nitrogen cycle
- 1) nitrogen fixation
- 2) ammonification
- 3) nitrification then nitrate
- 4) denitrification
What enzyme does nitrogen fixation require
Nitrogenase uses a lot of ___ and ___ to convert a single N2 molecules into organic nitrogen
ATP energy and electrons
___ needs an anaerobic environment, so oxygen interferes with it
only bacteria have___
____ bacteria are free-living nitrogen-fixing bacteria
free living nitrogen-fixing bacteria: ___ have specialized ____.
Specialized cells in ____ create a microenvironment where nitrogen fixation can take place on called ____
cyanobacteria, heterocysts have specialized membranes.
most cells in cyanobacteria perform
photosynthesis and respiration, except heterocysts.
photolithoautotrophic free-living nitrogen fixation bacteria are called _____, and require ____for respiration
cyanobacteria, require oxygen
Name a nitrogen-fixation chemoheterotrophic bacteria that live in an anaerobic environment on root nodules.
Rhizobium form a ____ symbiotic relationship with plants
Rhizobium spp are (aerobic or anaerobic) bacteria which live in an (aerobic or anaerobic) environment on the root nodules in the plant
aerobic bacteria that live in anaerobic environment.
Plant supplies oxygen to bacteria in a controlled way through ____, so it will not interfere with nitrogenase
Legume hemoblobin (leghemoglobin) carries oxygen to bacteria from plant, which prevents nitrogenase from coming in contact with oxygen.
___ is toxic to many things at high concentration, so what cycle quickly follows?
Ammonia, nitrification converts ammonia to nitrite.
2 steps in nitrification
- 1st step: ammonia oxydation
- 2nd step: nitrite oxydation
1)ammonia oxidation converts
2)Nitrite oxidation converts
- 1)bacteria converts ammonia into nitrite
- 2) bacteria converts nitrite (food) into nitrate (waste)
-an anaerobic process which offen occurs in wetlands and other riparian (water) regions and waste water treatment facilities.
-This process can become overwhelmed if there is a large amount of nitrates in the environment (e.g. from fertilizer usage).
Nitrate leaching is another name for
What is the result of nitrate leaching? example
- excess of nitrates cause algae bloom,followed by bacterial bloom which causes loss of oxygen in water and death of plants and animals in/near water.
- (example Red Tide).
Eutrophication is the
excess of nitrate causing algae bloom, followed by bacterial bloom, loss of oxygen and death of plants and animals
How do carbon atoms become accessible to living atoms through the carbon cycle?
photosynthetic plants in ocean and on land convert inorganic carbon into organic carbon.
Both routs of converting inorganic carbon into organic carbon rely on ____