Bio Exam 3 Review...

Bio Exam 3 Review... - Chapter 21 Changes in Earth's...

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Chapter 21 Changes in Earth’s atmosphere over time and causes of these changes. o O 2 increased when certain bacteria evolved the ability to use H 2 O as a source of oxidation reactions to synthesize ATP. When O 2 first appeared it was poisonous. Atmospheric O 2 made possible larger and more complex cells (Eukaryotes) Chronosequence of the geological eras from oldest to youngest. o Eras Periods Precambrain Cambrian (4.5 bya-600 mya) Palezoic Cambrian (542-297 mya) Ordovicion (488-444 mya) Silurian (444-416 mya) Devonian (416-359 mya) Carboniferous (359-297 mya) Permian (297-251 mya) Mesozoic Triassic (251-200 mya) Jurassic (200-145 mya) Cretaceous (145-65 mya) Cenozoic Tertiary (65-1.8 mya) Quaternary (1.8-Now….) How half-lives of isotopes are used to estimate ages of fossils. o Radioisotopes are used to determine the actual age of rocks. The half-life is the time interval over which ½ of the remaining radioisotopes are used to determine the actual age of rocks. In each half-life 50% of the parent atoms decay into daughter atoms. Causes of Mass Extinctions o Sea levels dropping, Meteorite Impacts, Drifting Continents, Volcanic Activity Implications of continental drift, climate, and atmospheric changes for evolution. o Movement of lithosphere plates caused continental drifting.
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o Sometimes the earth was considerably hotter than today; sometimes colder, with extensive glaciations. Climate changes have been very rapid. o Atmospheric O 2 was 1 st poisonous to the anaerobic prokaryotes, but when some evolved the ability to metabolize O 2 aerobic metabolism was faster and more energy was harvested. Aerobes replace anaerobes in most environments. Atmospheric O 2 also made possible larger and more complex cells. How we use the chemical composition of rock strata to infer past events, such as meteorites striking the earth. o
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Bio Exam 3 Review... - Chapter 21 Changes in Earth's...

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