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Page 1. EQ’s 1-4. What happened at the Cambrian Explosion? What happened at the K-T Boundary? What were the first type of organisms on Earth? What does the endosymbiont theory?. Page 1.

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  1. Page 1

  2. EQ’s 1-4 • What happened at the Cambrian Explosion? • What happened at the K-T Boundary? • What were the first type of organisms on Earth? • What does the endosymbiont theory?

  3. Page 1 Land Conditions: Earth was molten lava to start. Gravity started pulling elements together. Crust started to form

  4. Page 1 Atmosphere conditions: Probably were gases expelled from volcanoes (water, CO2, sulfur dioxide)

  5. Page 1 MODERN EVIDENCE OF EARLY LIFE Fossils- Any preserved evidence of an organism by mineral replacement, molds/casts, ice mummies or amber.

  6. Page 1 How does a fossil form? Organism must die and be covered in sediment quickly (near moving water).

  7. Page 1 On what parts of the Earth do we find fossils? Areas that were moving, shallow water when those organisms lived.

  8. Inside of cover Steps to Fossils • Organism dies near/in water • Quickly covered in sediments

  9. Inside of cover • Flesh decays, more sediments • Minerals harden in the bones

  10. Inside of cover 5. Bones decay, only minerals are left

  11. Page 2 HOW OLD ARE THESE FOSSILS? Relative Dating- Method used to determine the age of rocks by comparing them with other layers.

  12. Page 2 Radiometric dating- Uses the decay of radioactive isotopes to measure the age of a rock.

  13. Page 2 Half-life- the known amount of time it takes for half of the original isotope to decay (Uranium238 to Lead 206)

  14. Page 3 How is the time scale organized? It expresses the major geological and biological events in Earth’s history.

  15. Page 3 Eon- Time is split into PreCambrian and Phanerozoic.

  16. Page 3 Era- The next largest division (Dinosaurs=Mesozoic) Period- the divisions of an era.

  17. Page 3 Precambrian Era- The first 4 billion years on Earth, prokaryotes 1st then multicellular eukaryotes.

  18. Page 3 Paleozoic Era- Major diversification of body plans and # of species. Life in oceans 1st, then moved to land. 2 mass extinctions.

  19. Page 3 Mesozoic Era- Early mammals 1st, then dominated by reptiles (dinosaurs). 1st flowering plants and birds.

  20. Page 3 Cenozoic Era- Mammals are dominant life-form, diversified quickly

  21. Page 3 Cambrian Explosion- When ancestors of most animal groups diversified.

  22. Page 3 K-T Boundary- Layer between Mesozoic and Cenozoic eras. Evidence of impact event (iridium).

  23. Page 3 Plate Tectonics- Movement of large continental plates.

  24. Page 4 Origins of Earth Spontaneous Generation- Idea that life arises from non-life. Example- mice came from damp hay and corn

  25. Page 4 Theory of Biogenesis- Only living organisms can produce other living organisms.

  26. Page 4 How did complex molecules join together? Primordial Soup Hypothesis- If early Earth had mix of gases, organic cmpds could be made by reactions in the oceans.

  27. Page 4 Deep-Sea Vents- Some believe that these reactions began here, where sulfur forms the base of the food chain.

  28. Page 4 Order of Organic Molecule Organization 1. The first organic molecules originated

  29. Page 4 • Formation of proteins • Genetic code that could produce these proteins.

  30. Page 4 4. Formation of membranes, molecules become cells

  31. Page 4 Cellular Evolution 1. 1st cells were prokaryotes (bacteria), very simple with no nucleus or cell parts. Similar to archaea bacteria (thermophiles)

  32. Page 4 2. Photosynthesizing Prokaryotes- Archaea used sulfur for food, next organisms used light (photosynthesis)

  33. Page 4 3. Endosymbiont Theory- Ancestors of eukaryotes lived in association with prokaryotes. Explains DNA in chloroplasts and mitochondria.

  34. Page 5 Evolution- Idea that organisms CHANGE OVER TIME as a result of “genetic variations” enabling them to ADAPT to changing environments.

  35. Page 5 Evolution explains….. • How living things develop from ancestors

  36. Page 5 b. How Earth came to be populated by species

  37. Page 5 Evidence for evolution can be seen in…. • Cell similarities in all life • Similar proteins in all cells

  38. Page 5 • Many species disappearing from Earth • Living species being different from ancestors

  39. Page 5 • Organisms being suited to environments

  40. Page 5 • Extinction- When a species that once lived on the Earth no longer exists. Death rate is higher than birth rate

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