Chap 25

Cards (30)

  • The geologic record is a standard time scale dividing Earth’s history into the Hadean, Archaean, Proterozoic, and Phanerozoic eons.
  • The Phanerozoic encompasses most of the time that animals have existed on Earth.
  • The Phanerozoic is divided into three eras: the Paleozoic, Mesozoic, and Cenozoic.
  • Mass extinction is the result of disruptive global environmental changes
  • In each of the five mass extinction events, more than 50% of Earth’s species became extinct
  • The Permian extinction defines the boundary between the Paleozoic and Mesozoic. It caused the extinction of about 96% of marine animal species.
  • According to the theory of plate tectonics, Earth’s crust is composed of plates floating on Earth’s mantle.
  • RNA molecules called ribozymes have been found to catalyze many different reactions
  • Microfossils are fossilized forms of microscopic life
  • Life evolved into three monophyletic domains including Eubacteria, Archaea, and Eukaryotes.
  • The Miller-Urey experiment found within a week that methane gas converted into other simple carbon compounds. Concluded that key molecules of earth could have formed on early Earth.
  • Microfossils are fossilized forms of microscopic life
  • Stromatolites are mats of cyanobacterial cells that trap mineral deposits
  • Scientists estimate that the current rate of extinction is 100 to 1,000 times the typical background rate.
  • Extinction rates tend to increase when global temperatures increase
  • According to the theory of plate tectonics, Earth’s crust is composed of plates floating on Earth’s mantle
  • Compartmentalization of cells enabled the advent of eukaryotes
  • Multicellularity leads to cell specialization
  • Sexual reproduction allows greater genetic diversity
  • The first genetic material was probably RNA
  • Chloroplasts are derived from cyanobacteria
  • Mitochondria and chloroplasts entered early eukaryotic cells by endosymbiosis
  • The trigger for global glaciations was the drop in atmospheric carbon dioxide.
  • In order for the first cells to develop, a phospholipid-like molecule would be necessary so it can protect and concentrate the necessary molecules.
  • The Miller-Urey experiment showed that essential biological molecules associated with living organisms could be generated in an “abiotic” environment and conditions in the “primitive Earth environment” could have generated complex molecules.
  • Phosphorous increases the productivity of photosynthetic organisms and carbon fixation, thats why a mass release of phosphorous a potential explanation for glaciations.
  •  Mitochondria and chloroplasts provides evidence for their endosymbiotic origins because the mitochondria and chloroplasts have their own DNA.
  • Chloroplasts are likely descendents of photosynthetic bacteria and likely have an endosymbiotic origin.
  • Hadean Earth was not a hospitable environment for early life to evolve because of extremely hot/cold temperatures, volcanic eruptions and asteroid impacts.
  • The Cretaceous separates the Mesozoic from the Cenozoic.