The Precambrian Earth

Practice Test
      
  1.__________ are rocks that have alternating bands of fine-grained quartz and iron oxides.  
  a.   Red beds  
  b.   Sedimentary rocks  
  c.   All Archean rocks  
  d.   Banded iron formations  
      
  2.What continent existed around 1.8 billion years ago that now forms the core of modern North America?  
  a.   Pangaea  
  b.   North America  
  c.   Laurentia  
  d.   Rodinia  
      
  3.The oldest rocks on Earth are __________.  
  a.   1 to 2 billion years old  
  b.   3.5 billion years old  
  c.   1.6 to 1.8 million years old  
  d.   3.96 to 3.8 billion years old  
      
  4.According to the dates given in the table, when would oxygen start appearing in Earth's atmosphere?

Event Or First Evidence In Fossil Record Approximate Geological Time
Bacteria 3 b.y.b.p
Green algae 1 b.y.b.p
Jellyfish 600 m.y.b.p
Ediacara organisms 550 m.y.b.p
Eurypterids* 510 m.y.b.p
Horn corals* 500 m.y.b.p
First vertebrates 480 m.y.b.p
Spiders 400 m.y.b.p
Sharks

400 m.y.b.p
First jawed fish* 380 m.y.b.p
Ferns 350 m.y.b.p
Earthworms 300 m.y.b.p
Great Permian Extinction Event

250 m.y.b.p
Drastic geographic and climatic changes 248 m.y.b.p
First dinosaurs* 220 m.y.b.p
First mammals 210 m.y.b.p
Ginkgo biloba 200 m.y.b.p
Abundant ammonites* 180 m.y.b.p
Archaeopteryx* 140 m.y.b.p
First flowering plants 120 m.y.b.p
Ants 100 m.y.b.p
Cretaceous-Paleogene Extinction Event 66 m.y.b.p
Camel 35 m.y.b.p
Grass 20 m.y.b.p
Australopithecus afarensis (“Lucy”) 4 m.y.b.p


 
  a.   550 million years go  
  b.   600 million years ago  
  c.   3 billion years ago  
  d.   1 billion years ago  
      
  5.What was the original composition of Earth's atmosphere?  
  a.   ammonia and hydrogen  
  b.   nitrogen and carbon dioxide  
  c.   hydrogen and helium  
  d.   water vapor and methane  
      
  6.What evidence supports the hypothesis that Earth is 4.6 billion years?  
  a.   the age of rocks from the Moon  
  b.   the age of zircon grains in granitic crustal rocks  
  c.   all of the above answers are correct  
  d.   the age of meteorites  
      
  7.Why is the age of a zircon grain older than the age of the sandstone that it was found in?  
  a.   because of the principle of superposition  
  b.   because of the principle of included fragments  
  c.   It is much more stable than the sandstone.  
  d.   It is much less stable than the sandstone.  
      
  8.Which type of cell shown in the figure existed first?



 
  a.   B  
  b.   A  
  c.   both came into existence at the same time  
  d.   it is impossible to tell  
      
  9.What event caused the extinction of acritarchs near the end of the Proterozoic?  
  a.   outgassing  
  b.   formation of ozone  
  c.   the Varagnian glaciation  
  d.   global warming  
      
  10.According to the table, what were the first organisms to evolve on Earth?

Event Or First Evidence In Fossil Record Approximate Geological Time
Bacteria 3 b.y.b.p
Green algae 1 b.y.b.p
Jellyfish 600 m.y.b.p
Ediacara organisms 550 m.y.b.p
Eurypterids* 510 m.y.b.p
Horn corals* 500 m.y.b.p
First vertebrates 480 m.y.b.p
Spiders 400 m.y.b.p
Sharks

400 m.y.b.p
First jawed fish* 380 m.y.b.p
Ferns 350 m.y.b.p
Earthworms 300 m.y.b.p
Great Permian Extinction Event

250 m.y.b.p
Drastic geographic and climatic changes 248 m.y.b.p
First dinosaurs* 220 m.y.b.p
First mammals 210 m.y.b.p
Ginkgo biloba 200 m.y.b.p
Abundant ammonites* 180 m.y.b.p
Archaeopteryx* 140 m.y.b.p
First flowering plants 120 m.y.b.p
Ants 100 m.y.b.p
Cretaceous-Paleogene Extinction Event 66 m.y.b.p
Camel 35 m.y.b.p
Grass 20 m.y.b.p
Australopithecus afarensis (“Lucy”) 4 m.y.b.p


 
  a.   jellyfish  
  b.   ediacara organisms  
  c.   green algae  
  d.   bacteria  
      
  11.What was the composition of Earth's first crust?  
  a.   iron and quartz  
  b.   feldspar  
  c.   feldspar, quartz, and mica  
  d.   iron- and magnesium-rich minerals  
      
  12.Minerals with low densities crystallize from a magma at __________ denser minerals do.  
  a.   the same temperature as  
  b.   always 10 degrees less than  
  c.   cooler temperatures than  
  d.   hotter temperatures than  
      
  13.The inner and outer core, mantle, and crust of Earth all have __________.  
  a.   been rigid since the formation of Earth  
  b.   different densities  
  c.   the same densities  
  d.   have the same specific gravity  
      
  14.What did organisms of Earth's first 4 billion years have in common?  
  a.   They breathed oxygen.  
  b.   They were photosynthetic.  
  c.   They were multi-celled organisms.  
  d.   They were single-celled organisms.  
      
  15.What substance in Earth's atmosphere protects organisms from UV radiation?  
  a.   ozone  
  b.   methane  
  c.   ammonia  
  d.   water vapor  
      
  16.Why don't Archean and Proterozoic rocks have iron oxides?  
  a.   there was too much iron to be oxidized  
  b.   there weren't any stromatolites at that time  
  c.   there wasn't any iron in rocks of that age  
  d.   there wasn't any free oxygen in the atmosphere  
      
  17.How were asteroids and meteorites a heat source for Precambrian Earth?  
  a.   Their bombardment of Earth caused them to sink to the core.  
  b.   Their gravitational contraction generated energy.  
  c.   Their radioactive decay of isotopes generated energy.  
  d.   Their impact on Earth generated energy.  
      
  18.Fossils of __________ from late Proterozoic rocks are found in all parts of the world.  
  a.   the Burgess Shale fauna  
  b.   the Ediacaran fauna  
  c.   trilobites  
  d.   corals  

 
   
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