Ecology Week One
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This 4 page Class Notes was uploaded by Katlyn Burkitt on Saturday February 6, 2016. The Class Notes belongs to Biol 202 at Towson University taught by J. LaPolla in Spring 2016. Since its upload, it has received 99 views. For similar materials see Intro to Ecology and Evolution in Biology at Towson University.
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Date Created: 02/06/16
Chapter 26 Biology Notes Debris from a meteor hitting earth formed the moon (4.6 BYA) Atmospheric temperature is 2000˚C Increased CO2caused Increased temperature Decreased CO 2aused decreased Weathering increases in hot wet conditions and pulls2CO from the atmosphere Plates o Ridged slabs of rock that forms earths crusts Plate tectonics o The movement of plates Supercontinents o Rodinia: All continents, during the Proterozoic era (early life) Broke up during 650 MYA o Gondwana: All southern hemisphere continents o Pangea: All continents Phanerozoic = Visible life o 12% of earth’s history Paleozoic era/ Cambrian period = High diversification of multicellular life Birds and mammals o 4% of earth’s history Humans o .2% of earth’s history Fossils are dated by the half-life’s of their isotopes o Carbon dating, uses carbons half-life which is 5700 years How did life originate? o Arose from early waters filled with ammonia, formaldehyde, folic acid, cyanide, methane, hydrogen sulfide, and organic hydrocarbons o Meteorites may have brought some of the organic molecules Example Tagish with 3% of its mass being organic molecules o Reducing Atmosphere (high hydrogen content) Makes forming molecules easier o Miller and Urey Experiment Step 1: Assembled a reducing atmosphere Step 2: Placed atmosphere over liquid water Step 3: Maintained at a temperature bellow 100˚C Step 4: Simulated lightning This created small organic molecules and amino acids RNA was the first nucleic acid that promoted self-replication Early membranes were made of fatty acids Craton: A rock layer of undisturbed continental crusts o Microfossils Stromatolites: Sedimentary deposits held in place by mats of micro-organisms Carbon Fixation: Changing inorganic carbon to usable organic carbon o Done by the Calvin Cycle and the reductive Krebs cycle Organic molecules are biomarkers o Example Hydrocarbons from fatty acids Climate: Temperature and water availability Atmosphere: Levels of 2 and CO2 o Volcanic Eruptions alter the atmosphere Highest temperature of earth was 2000˚C Lowest temperature of earth was -50˚C Snowball Earth: Ice or glaciers Glaciation results in massive extinctions Oxygenic photosynthesis produced O e2couraging the evolution of cellular respiration Increased O2in the atmosphere caused O t2 interact with UV rays forming O 3r Ozone Lecture Notes 2-3-16 1 Eon: Hadean (4.6 to 4bya) o Beginning of a cooling earth o No liquid water o CO2levels dropped and liquid water formed marking the end of the Hadean eon 2 Eon: Achaean (4bya to 2.5bya) o The first living things appeared as single celled organisms o The Atmosphere of earth changed rd 3 Eon: Proterozoic (2.5bya to 542mya) o Multicellular life emerges o Continued changes in earths atmosphere 4 Eon: Phanerozoic (541mya to the present) o Changes in the multicellular life o Extensive diversity o Cambrian period Begins with complex multicellular life The weathering of rock pulls CO2from the atmosphere where it mixes with water to form H C2 3 or hydrochloric acid which comes down in the form of acid rain and reacts with the rocks and travels down into the ocean where it reacts with 2a to form CaCO3which forms the bodies of many organisms such as shellfish. Fossils o Rock fossils: Organisms barried in sediment Their tissues mineralized Calcium bone/shells Surrounding sediment hardens into rocks o Amber Fossils Fossilized tree resin Things are caught in the resin These fossils are younger along about 120mya o How are they dated Through Stratigraphy which produces a relative age The most recent fossils typically are the most recent Through Radioactive decay which produces and absolute age Radioisotopes o They are unstable and break down into something else through a half life o A half-life is where one half of the original isotope has turned into the daughter isotope 14 14 o Examples: C turns into N over the course of 5730 years 238 206 U to Pb over the course of 4.5bys
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