Astronomy 2021A/B Study Guide - Midterm Guide: Palermo Technical Impact Hazard Scale, Manicouagan Reservoir, Dinos
25 Nov 2016
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**three lines of evidence that life began bw 3. 85-3 by a. Stromatolites: rocks characterized by a distinct layered structure. Microfossils: structures in photo may be ancient fossil cells, dating to 3. 5 by a, chemical analysis also revealed organic carbon, assumed to have resided in a sedimentary rock in a shallow sea (possibly early photosynthetic organisms, however: Subsequent analysis shows rock is not from a shallow area, but from near a deep-sea volcano vent. Hence, cell would not have been photosynthetic. Perhaps not a fossil at all, but a non-biological structure: microfossil evidence for life by 2. 7-3 by a is stronger. Contain a type of hydrocarbon molecule almost certainly associated with life: hence, microfossil record suggests life originated by 3. 5-3 by a. Isotopes of carbon: living organisms change the ratios of isotopes from their naturally occurring ones, ex. carbon-12 and carbon-13.
