LIFESCI 2H03 Lecture Notes - Magnetite, Ferrous, Hematite
24 Feb 2013
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Document Summary
The prebiotic earth probably has a atmosphere dominated by co2 and n2. A lager change in the atmospheric composition occurred when organisms evolved that were able to perform oxygenic photosynthesis: this lead to the establishment of our modern o2-rich environment. We still do not know how life originated but we know when, due to the apex. 3. 5 bya layers of stromatolites started to form, these stromatolites are the fossilized remains of bacteria: the areas where these stromatolites formed is similar to the shark bay on the coast of western australia. Although we know that the organisms that formed stromatolites were photosynthetic we do not know if they produced o2 as by-product: oxygenic photosynthesis is carried out by higher plants and algae today. Some bacteria make their living by a related process called anoxygenic photosynthesis. In this process h2s or h2 is used instead of h2o to reduce.
