18. Evidence For Life On Early Earth +history Of Earth (go Over) Flashcards
What is morphological evidence
Fossils of microorganisms , sedimentary structures produced by life
What is molecular evidence?
Remains of organic macromolecules (lipids)
What is isoptpic evidence ?
Anamalpus concentrations of stable isotopes?
What are stromatolites
Domes columns and cones of living rock preserved over time
Are GA Apex chert fossils oldest on earth?
Found that there not fossils, as not in the right environment and appear to be exfoliated by mineral grains
Are tubule tribulations oldest fossils?
Claims that Tubules from Lava erupted from sea floor claims they’ve been etched by microorganisms, Debunked not to do with life
Is morphology a good source for oldest fosisil?
At micro scale it’s very ambiguous, at this scale mineralogical structures can look alike and inorganic structures can just be coated in organics. A problems for the search for life on mars
What are bio markers /molecular fossils
Bio markers are the cores of ancient bio molecules (usually polycyclic lipids)
Are biomarkers helpful for finding oldest life on earth?
No, they have been heated so much in millions of year to be preserved enough
What are isotopes
Atoms of the same element elements with same number of protons but diff number of neutrons
Mass spectrometers to measure proportions of isotopes in a given substance compared to standard
Mass dependant isotope fractionation
Isoptopes of same element differ in mass
Lighter weaker bonds react faster so products of phase changes have diff compositions
Means they separate? Look up
How can we use carbon isotopic fractionation as life evidence?
Shows photosynthesis coures
??? Look up
Most ancient isoptopic evidence for
Idea.?
Some lighter carbon potentially shows it ?
Key lessons for search for life on mars?
Missions looking for fossils
Individual lines of evidence are ambiguous
Potentially on mars rocks could be more well preserved and that’s all we need to know
