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Unformatted text preview: for life. e.g. C, N
b) Nitrogen Cycle
- Key steps performed only by prokaryotes.
* Nitrogen fixation = only biological mechanism that
makes atmospheric nitrogen available to organisms for
incorporation into organic compounds.
c) Only organisms able to metabolize inorganic
molecules containing elements such as Fe, S, N, H. 2. Primary Production
blue-green algae - Autotrophic bacteria e.g. cyanobacteria make organic
compounds (food) from CO2 supporting food chains.
3. Symbiotic Relationships
Ex. Cellulose breakdown
huge component in a plant based diet 4. Historic Oxygen Revolution
- Cyanobacteria put all oxygen in atmosphere ~2.5 billion
- Allowed aerobic respiration....
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