test 3 lecture 16 Flashcards
(50 cards)
what does abiogenesis or biopoiesis or Ool mean
the natural process of life arising from non-living matter, such as simple organic compounds
before the first cells could evolve , what fundamental conditions were needed
essentail elements
continual source of energy
temperature range permitting liquid water
why were essential elements needed for origins of life
to compose organic molecules
why was a continual source of energy needed for origins of life
life requires continual input of energy, which ultimately is dissipated as heat
why was temperature range permitting liquid water needed for origins of life
metabolic reactions cease at temps that are either too high or too low
when was the solar system formed
4.6 billion years ago
what made up the early atmosphere
primarily of CO2
what makes up the atmosphere now
CO2, N2, and O2
how do we have the compounds in the atmosphere now
contributions from living organisms
heavy metals created from bursting stars
how did temp affect the atmosphere
atmospheric gases absorb light and convert the energy to heat, raising the temp of the surface and atmosphere
what could have caused the green house effect
early atmosphere had high CO2 making it very hot
what kept the atmosphere temp down in the beginning of time
CO2 rose temp but with microbial consumption of CO2 and produce N2 and O2 kept temp down
possibly causing ice age
when was the hadean eaon
4.5 to 3.8 billion years ago
what happened during the hadean eon
repeated bombardment of meteorite
cycles of vaporizing ocean, cooling and condensation
when was the archean eon
3.8 to 2.5 billion years ago
what is significant during the archean eon
earths crust become solid
marked first period of stable oceans
earliest geological evidence for life from rock strata
what is the key ingredient of life during early earth’s existence
liquid over range of temps and dissolves inorganic and organic material
what is stromatolites
the earliest forms of life (bacterial communities) for which we have clear fossil evidence
how are stromatolites formed
layers of phototrophic microbial communities grew and died
what are the different layers of stromatolites
outside: oxygenic phototrophs (diatoms, cyanobacteria)
inside: sulfate reducing bacteria
what do stromatolites not reveal
they are deformed and dont reveal cell structures
what are the 4 geological evidences for early life
stromatolites
microfossils
biosignatures/ biological signatures
oxidation state
what is the most convincing evidence of early microbial life
microfossils
what is in a microfossil
minerals precipitated and filled in the form of ancient microbial cells
