Review for the Second Midterm

This exam covers the material from the April 29 -- May 24 Lectures

What to really know and what are the key concepts?

Galaxies and Supernova

• Different kinds of Galaxies: Spirals vs Ellipticals
• Formation of elements via fusion --> up to Iron
• Formation of elements beyond Iron; Neutron Capture
  • R-process vs S-process
  • Formation of Uranium
  • Seeding the Galaxy with heavy elements
• Supernova are the Cosmic Womb and the means by which the Universe is connected

Formation of the Earth:

• Chemically enriched dusty disk forms around the Sun
• Temperature Gradient in this disk means dense planets form close to the sun and low density objects form far from the Sun
• Planets form via 4-step accretion process
• Left over debris craters the newly formed planetary surfaces
• How did the earth get its water?
• Jupiter and cometary bombardment
• Where did the moon come from? Significantly different density than the Earth?
• Supercomputer tells us that a collision with a Mars sized object with the molten proto-earth produced debris that coalesced to form the moon -- pretty wild but seems to be the only way to account for its anamolous density

Evolution of the Earth's Atmosphere

• Original Atmosphere of Hydrogen and Helium lost
• Secondary atmosphere composed mostly of CO₂ and water vapor
• Earth is at the right distance from the sun to produce a temperature conducive for the condensation of water vapor
• Condensation of the oceans and the dissolution of CO₂ into the oceans
• What happened to the water on Mars and Venus?
• Most of the earth's atmosphere now in the oceans leaving behind Nitrogen which is chemically inert and stays in the atmosphere.
• Trace amounts of methane and ammonia react with water and energy to produce simple amino acids which rain down into the ocean.

Formation of Life in the Oceans:

Nine Steps: ( Know the timeline )

1. Chemical synthesis of organic molecules --> monomers
2. Concentration of monomers to facilitiate the formation of polymers
3. trial and error combination of polymers until DNA is discovered. Microwave background --> uiverse is filled with photons at some characteristic temparture
4. Multiplying population for bacteria initially feeds off each other through fermentation process
5. Anerobic photosynthesis presents the first advantageous alternative to cells getting energy through fermentation
6. Chlorophyll evolves to more efficiently harness the energy from UV photons --> this leads to areobic photosynthesis with O₂ as a waste product
7. O₂ given off in the ocean no harmful to unprotected DNA. Fortunately dissolved Iron in the ocean scavanges the O₂ to make FeO₂ which settles out to the ocean floor
8. Gradually over 1 billion years or so prokaryotic cells evolve into eukaryotic cells in which the DNA is in the cell nucleus. O₂ is used as a catalyst for rapid cell division (mitosis) leading to the formation of multi-cellular creaters.
9. Eventaully all the FeO₂ settles out and the O₂ now can go into the earth's atmosphere which allows for the formation of the ozone layer

   Life On the Land:

   • 700 million years ago species begin to migrate from the Sea to the Land
   • Land is an unstable ecosystem on long timescales
     • Plate Tectonics --> volcanoes and earthquakes; continental drift and disruption of migration patterns
     • Climatological catastropher --> Big Ice Ages
     • Mass Extinctions --> 2/3 of all species extinct. Affects both ocean and land life.

   • Slow evolution of relative intelligence in response to environmental stimulation.
   • Species diversification aids the development of intelligence
   • Fossil record and encyphlization level
   • Is there intelligent life on the Earth?
   • How do we define intelligence?
   • Grid Patterns 'R Us.

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   The Electronic Universe Project
   e-mail: nuts@moo.uoregon.edu