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18 Cards in this Set
- Front
- Back
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Oldest fossil
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3460 MA
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Stromatolite
What is it? Why is it rare? How they form? |
- Laminated structures of bound sediment and carbonate
- live in inhosbitable conditions - can't compete for resources - form in two ways: microbial binding of sediments and precipitation of mineral laminae |
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Body fossils
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"actuall evidence"
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Cyanobacteria
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• group of prokaryotes that use oxygenic photosynthesis
• 2700 MA |
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biomarkers
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"chemical evidence of organism"
i.e - sterols |
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origins of oxygenic photosynthesis
ages? |
body fossils (cyanobacteria) - 2700 MA
biomarkers (Detrital reduced minerals ) - 2400 MA BIF - 3500 MA |
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Prokaryotes
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-older:
- no cell nucleus -DNA not arranged in chromosomes - small cells |
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Eukaryotes
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-communites of prokaryotes
- cell nucleus w/ double membrane - dna arranged in chromosomes - large cells |
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endosymbiotic
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one organism lives inside the other
o Many benefits – protection and sharing |
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Banded Iron Formations (BIFS)
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• Oxidized iron
o When iron is oxidized and then becomes part of sediment, the sediment turns red – forms sedimentary rock • Less oxygen in atmosphere Next piece of iron has less oxygen to react with • It is not red • When cyanobacteria creates oxygen → atmosphere has more oxygen Next piece of iron reacts w/ iron → turns red • Evidence for oxygen in Precambrian period • Although this takes place in ocean – atmosphere still gets o2 |
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Acritarchs
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• Unicellular eukaryotes
• One of oldest eukaryotes • alive from Precambrian – present |
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Gradual evolution
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AkA microevolution:
slow rate of evolution specie variation |
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Punctuated equilibrium
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no change through time
then rapid change little to no intermediates |
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requirements of living things
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oxygen, water and liveable environment
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oldest body fossil
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cyanobacteria found 2000 MA in Belcher Islands, Canada
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division of precambrian
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precambiran
archean proterozoic paleoproerozoic mesoproterozoic neoproterozoic ediacaran |
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mitochondria
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makes energy for cell
in eukaryotes |
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chloroplast
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organeles that allow photosynthesis
in eukaryotes |
