The History of Life Notes2

The History of Life Notes2 - celled prokaryotes(bacteria 2...

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T HE  H ISTORY   OF  L IFE - Earth is estimated to be approximately 4.6 billion years  old. At this time, the earth was inhospitable- it was very  hot, the atmosphere was made up mostly of water vapor,  carbon dioxide, and nitrogen (very little oxygen)  - Scientists study fossils to provide insight on when the  first organisms formed. A fossil is a preserved or  mineralized remains (bone, tooth, or shell) or imprint of  an organism that lived long ago.  - 3.5 billion years ago- The first forms of life were single-
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Unformatted text preview: celled prokaryotes (bacteria). 2 groups of bacteria existed: o Archaebacteria: “ancient bacteria”; rare today; found mostly in hostile environments similar to conditions that resembles the ancient earth o Eubacteria: “true bacteria”; includes most bacteria that cause disease and decay. One type of eubacteria is cyanobacteria, which is able to photosynthesize and release oxygen into the atmosphere....
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