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Earth and Space Unit 3 Review PowerPoint Presentation
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Earth and Space Unit 3 Review

Earth and Space Unit 3 Review

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Earth and Space Unit 3 Review

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  1. Earth and Space Unit 3 Review • What is the difference between geosphere and the lithosphere? • ANS: The geosphere is the solid portion of the Earth, and includes the lithosphere (which only includes the planet’s crust, and upper mantle.) • 2. Which of Earth’s systems would gaseous H2O belong in (list all please) • ANS: The atmosphere; the hydrosphere • 3. The most prevalent gas in today’s atmosphere is… • ANS: Nitrogen (diatomic molecule N2)

  2. What gas wasn’t present in Earth’s early atmosphere that is now present, making aerobic life possible? • ANS: Oxygen • Describe one reason why the gases in Earth’s first atmosphere (hydrogen and helium), were lost to space. • ANS: Earth wasn’t differentiated yet, and therefore had no magnetosphere, so the sun’s solar wind could have “blown” it away. Also, these elements are very light and may have just dissipated into space. • 6. What is probably the origin of Earth’s second atmosphere? (Containing CO2, SO2, CO, S2, Cl2, N2, H2) and NH3 (ammonia) and CH4 (methane) • ANS: Volcanic outgassing

  3. Describe one way that Earth’s Oceans could have formed. • ANS: Comets delivered the water; Outgassing of H2O from volcanic activity; followed by torrential rain from condensation in the atmosphere • How much of today’s atmosphere is oxygen? • ANS: 21% • What is photochemical dissociation? • ANS: Occurs when UV radiation breaks up water, creating O2 and hydrogen. • What evidence is there in the rock record that oxygen was present at any point in the atmosphere? • ANS: Iron oxide (rust) present, means water and oxygen was present. BIFs and red beds, which are rocks that are completely red

  4. 11. Why is there so much N2 in our atmosphere today? ANS: Because it is relatively chemically inactive, and just sticks around as a result 12. What outgassed molecule chemically reacted with the O2 produced through photochemical dissociation, helped to created even more nitrogen in our atmosphere? ANS: Ammonia (NH3) 13. Where is Earth’s biosphere? ANS: It is above, on, and under the surface of the Earth…wherever there is life. 14. Why is the formation of ozone (O3) so important to Earth’s biosphere? ANS: Ozone in the stratosphere protects living things from dangerous UV radiation.

  5. 15. What are anaerobes? ANS: Organisms that usually die in the presence of oxygen 16. Why do scientists think these anaerobes were the first forms of life on Earth? ANS: because there was no free oxygen in Earth’s early atmosphere, aerobes (organisms that need oxygen) could not have lived there. 17. What gases did these early anaerobic “methanogens” require to survive (Why was early Earth a “paradise” for them? ANS: CO2 and Hydrogen 18. Cyanobacteria were one of the first life forms to use this process to add oxygen to the atmosphere. ANS: Photosynthesis

  6. 17. Cyanobacteria are also important because of their contributions to the cycling of nitrogen. Why is nitrogen important to the biosphere? ANS: Nitrogen is an important ingredient in the biomolecule protein…which is made of amino acids bearing nitrogen. Nitrogen is important because proteins build animal and plant bodies 18. From the initial GOE, and for the next two billion years after it, what happened on Earth? ANS: We have no idea! 19. Where is the Earth’s crust thicker, under the continents, or the ocean? ANS: Under the continents.

  7. 20. What is the name of the “plastic” part of the mantle that contains the convection currents that drive the Earth’s tectonic plates? ANS: Asthenosphere 21. What form of energy transfer occurs when we snuggle? ANS: Conduction 22. How is energy transferred through the vacuum of space? ANS: Radiation 24. Which of our Oceans is getting larger because of a mid-ocean ridge? ANS: Atlantic

  8. 25. When Earth’s atmosphere began changing, and the GOE occurred, what happened to the anaerobes? ANS: They either became extinct, or they moved to extreme environments on Earth where little if any oxygen exists. 26. Using the table to the above, you can see what types of gases are prevalent in today’s volcanic outgassing. What geological principal tells us it was the same on early Earth? ANS: Uniformitarianism 27. Which of these gases would have been most helpful to cyanobacteria? ANS: CO2