midterm review

• What is the first event in the timeline of life on Earth?

  Big Bang formed the universe
• How long ago did our solar system form?

  4.6 billion years
• When did Earth form?

  4.55 billion years
• How long ago did Earth cool enough for oceans to form?

  4 billion years
• When did life emerge on Earth?

  4 - 3.5 billion years
• What three components are essential for life?

  DNA, RNA, and proteins
• From where do living cells originate?

  From pre-existing cells
• What are the four overlapping stages of life's emergence?

  1. Nucleotides and amino acids produced
  2. Polymerization to form DNA, RNA, proteins
  3. Polymers enclosed in membranes
  4. Membrane-enclosed polymers evolved cellular properties
• What hypothesis explains the primitive atmosphere of Earth?

  Reducing Atmosphere Hypothesis
• What gases were present in the primitive atmosphere?

  H2O vapor, N2, CO2
• What was the condition of Earth before it cooled?

  Originally too hot for liquid water
• What is primordial soup?

  Condensed liquid water with organic molecules
• What did Miller and Urey demonstrate in their experiment?

  Biochemicals could be produced from nonbiological sources
• What year did Miller and Urey conduct their experiment?

  1953
• What conditions were used in Miller and Urey's experiment?

  Primitive atmospheric gases and strong energy sources
• What did Miller and Urey's experiment yield?

  HCN, CH2O, glycine, sugars, amino acids
• What is the Extraterrestrial Hypothesis?

  Organic carbon from asteroids stocked prebiotic soup
• What do meteorite studies suggest about organic carbon?

  Carbonaceous chondrites contain organic carbon
• What is the Deep-sea vent Hypothesis?

  Key organics arose at deep-sea vents
• What conditions exist at deep-sea vents?

  Superheated water rich in H2S and metal ions
• What is the Clay hypothesis?

  Simple organics polymerize on solid surfaces
• What are protobionts?

  Cell-like structures with boundary and polymers
• What functions do polymers inside protobionts serve?

  Contain information and enzymatic function
• What is the significance of RNA in protobionts?

  Can store information and replicate
• What are stromatolites?

  Mats of mineralized cyanobacteria
• What are the advantages of the DNA/RNA/Protein world?

  • DNA relieves RNA of informational role
  • DNA is less prone to mutations
  • Proteins have greater catalytic potential
  • Proteins perform various cellular tasks
• What are fossils?

  Remains and traces of past life
• What is paleontology?

  The study of the fossil record
• How are most fossils formed?

  Embedded in sediments that convert to rock
• What do strata of the same age contain?

  Similar fossil assemblages
• How do geologists determine relative dates of fossils?

  By examining strata and fossil assemblages
• What is an index species?

  A species with wide distribution
• What factors affect the fossil record?

  Environmental conditions and organism characteristics

  
• What is absolute dating in fossils?

  Determining age using radioactive decay
• What is half-life?

  Time for half of a radioactive substance to decay
• What is the half-life of Potassium-40?

  1.25 billion years
• What is the half-life of Carbon-14?

  5730 years
• What is the half-life of Uranium-238?

  4.47 billion years
• What is the half-life of Uranium-235?

  713 million years
• What is the half-life of Rubidium-87?

  48.8 billion years