1 A) They represent the presence of red and brown algae in the oceans. B) They show that the buildup of sediments was continuous during that time. C) They confirm that iron was present in the sediments when they were deposited. D) They show that the composition of the atmosphere changed to contain oxygen. 2 A) DNA and RNA B) Amino acids C) Formaldehyde molecules D) Cyanide molecules 3 A) oxygen B) soil C) water D) sunlight 4 <![CDATA[<a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=gif::::/sites/dl/free/0078746361/561661/au.GIF','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (21.0K)</a>]]> A) Archean B) Paleozoic C) Proterozoic D) Mesozoic 5 A) iron B) water C) air D) quartz 6 A) ediacara organisms B) bacteria C) jellyfish D) green algae 7 A) Their impact on Earth generated energy. B) Their bombardment of Earth caused them to sink to the core. C) Their gravitational contraction generated energy. D) Their radioactive decay of isotopes generated energy. 8 A) 3.5 billion years old B) 3.96 to 3.8 billion years old C) 1.6 to 1.8 million years old D) 1 to 2 billion years old 9 A) Canadian shields B) continental crust C) Archean shields D) Precambrian shields 10 A) Laurentia B) North America C) Pangaea D) Rodinia 11 A) They were single-celled organisms. B) They were multi-celled organisms. C) They breathed oxygen. D) They were photosynthetic. 12 A) the oldest fossils B) zircon grains in Precambrian aged rocks C) impact craters on Earth D) thickest layers of sedimentary rocks 13 A) the Archean Shield B) the Northern Shield C) the Proterozoic Shield D) the Canadian Shield 14 A) ammonia B) water vapor C) ozone D) methane 15 <![CDATA[<a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=jpg::::/sites/dl/free/0078746361/561693/129_yrsago_noart23.jpg','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (21.0K)</a>]]> A) Rodinia B) Pangaea C) Laurentia D) Gondwana 16 A) ammonia and hydrogen B) hydrogen and helium C) water vapor and methane D) nitrogen and carbon dioxide 17 A) prokaryotes B) eukaryotes C) algae D) fungi 18 A) There weren't any stromatolites at that time. B) There wasn't any free oxygen in the atmosphere. C) There wasn't any iron in rocks of that age. D) There was too much iron to be oxidized. 19 A) raised the temperature of Earth's interior B) kept life forms from evolving C) made the atmosphere radioactive D) slowed the rotation around the axis 20 A) dammed up rivers and caused flooding B) prevented plants from growing C) stopped heat from escaping to space D) caused earthquakes and volcanic eruptions
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