BIO Chapter 25

BIO Chapter 25 - Chapter 25 Wednesday, January 28, 2009...

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Wednesday, January 28, 2009 1:45 PM THE HISTORY OF LIFE ON EARTH 1. Early Earth o Earth is about 4.6 billion years (BY) old Radiometric dating of meteorites and moon rocks o Life arose about 3.8 BY ago Chemical traces in rocks 3.8 BY Fossil bacteria in rocks 3.5 BY o No spontaneous generation now, but must have happened then. 2. Conditions on Early Earth o Atmosphere CO 2 ; CH 4 ; NH 3 ; H 2 S; H 2 O No free oxygen o Abundant energy to drive reactions Frequent storms w/ much lightening Frequent volcanic eruptions Frequent meteor impacts UV light from the sun o Is the following statement a scientific theory? Life on Earth arose as a result of physical-chemical processes. Yes o Is the following statement a scientific theory? Life is so complex that it must have been created by a supernatural being. No 3. Testable hypotheses explaining the origin of life o Abiotic synthesis of small organic molecules o Joining these molecules into polymers
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This note was uploaded on 01/29/2009 for the course BIOL 1202 taught by Professor Gregg during the Spring '08 term at LSU.

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BIO Chapter 25 - Chapter 25 Wednesday, January 28, 2009...

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