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BIO 101 Week 5 Notes

by: Toree Friedrich

BIO 101 Week 5 Notes BIO 101

Marketplace > Indiana State University > Bioogy > BIO 101 > BIO 101 Week 5 Notes
Toree Friedrich

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These notes are from week 5, 9/21 and 9/23. They will be on the next exam and the next quiz.
Biology 101
Steven L.Lima
Class Notes
history, Of, life, on, EARTH, Biology
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This 3 page Class Notes was uploaded by Toree Friedrich on Sunday September 25, 2016. The Class Notes belongs to BIO 101 at Indiana State University taught by Steven L.Lima in Fall 2016. Since its upload, it has received 5 views. For similar materials see Biology 101 in Bioogy at Indiana State University.


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Date Created: 09/25/16
9/21 Lecture Notes A History of Life on Earth  HANDOUT → geological eras and periods *MUST MEMORIZE*  Points on Rocks  Sedimentary Rocks  Form mud, clay, sand, and gravel  Contains fossils  Cannot be dated or aged directly  Age is determined by fossils  Igneous Rocks  Form from lava, magma → melted rocks  Contain no fossils  Can be aged with radioactive elements  How to get an absolute age of rocks  Use radioactive decay  Radioactive decay rates are constant  Key elements  C → N Age range: 100 – 50,000 years ago  Information is in 14C/12C ratio  High ratio: young  Low ratio: old  K → Ar Age range: 10 million – 4.5 billion years ago  Information is in K/Ar ratio  U → Pb Age range: 10 million – 4.5 billion years ago  Information is in U/Pb ratio  **FOR IGNEOUS ROCKS**  Age of earth: 4.54 billion years  Changing Conditions on Earth → Important for Life  Changing Ocean Levels  Volcanic activity and climate change  Major drops in ocean associated with extinctions  Indiana was below sea level for a long time  Climate Change → Huge Influence on Life  Temperature  Major swings in global temperature over time  Very warm and very cold periods  “Snowball Earth” – 650 million years ago the Earth was completely frozen  Oxygen (O2) Levels Over Time  Increased dramatically over time  Very low up to 2­2.5 billion years ago  O2 increased markedly with the evolution of photosynthetic bacteria  (cyanobacteria)  O2 is given off as a byproduct of photosynthesis  “Oxygen Catastrophe” of Precambrian Era  O2 is toxic  Increased O2 killed off many microbes  Much of life today descended from a microbe adapted to O2  Some Points About O2  High O2 made large life possible  High energy use with O2  O2 made life possible on land  O2 produces O3 (Ozone)  O3 removes much of UV light reaching Earth from the sun 9/23 Lecture Notes  PreCambrian (4.5 b.y.a – 542 m.y.a)  Origin of life – roughly 3.5 billion years ago  Bacteria are first clear organisms in fossil record  But claims of very old bacterial fossils much often debated  Photosynthetic bacteria – 2.2 – 3 b.y.a at least  Clear cyanobacteria stroma to lite fossils 2.8 billion years old  Multicellular organisms – 600­700 million years ago  Paleozoic Era (“Old Life”)  Cambrian Period – 542­488 million years ago  The “Cambrian Explosion”  Relatively rapid diversification of macroscopic life (that actually started in the  late Precambrian)  Almost all of the major clades (or phyla) still present today have their origin in the  Cambrian Explosion (or earlier)  Famous examples of “explosion” fossils from the Burgess Shale fossil bed in Alberta, Canada  Mid­Cambrian – 505 million years ago  Ordovician Period – 488­444 million years ago  No macroscopic life on land (everything is still in the ocean)  Major radiation of marine organisms  End of Ordovician is marked by a major mass extinction  But most types of life survive  Silurian Period – 444­416 million years ago  Marine diversification continues  Jawless fish diversify and become dominant vertebrates (many species)  First modern fish appear (they had jaws and rayed fins)  First plants appear on land by the end of the period  Devonian – 416­359 million years ago  Jawed (modern) fish diversify and replace most jawless fish   Many heavily armored  Many large cephalopods (squids) as major predators in oceans  First “forests” on land  Major diversification of arthropods on land  Centipedes, spiders, mites, insects, etc.  First amphibians appear on land  Represent a major branching of the vertebrate phylogenetic tree   Devonian ends in another mass extinction  But most types of life forms survive


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