Lecture 4 Water and Civilization

Lecture 4 Water and Civilization - 1 Water, Life, Humans,...

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Unformatted text preview: 1 Water, Life, Humans, and Civilization Must survive in low-oxygen environments Could not eat other organisms for food The First Organisms Two energy sources: Light and Chemical reactions Light: photoautotrophs Chemical reactions: chemoautotrophs Assemble complex carbon compounds from simple Carbon compounds (CO 2 ) using external energy. The First Organisms The First organisms: Chemoautotrophs (Fe and S) microtubes in pillow lavas containing residual carbon Evidence: Light: photoautotrophs Chemical reactions: chemoautotrophs 2 Must survive in low-oxygen environments Could not eat other organisms for food The Early Organisms Photosynthesizers: photoautotrophs Blue-green algae/cyanobacteria- Removal of carbon dioxide- production of oxygen Earliest: Main effects: The Early Organisms Oldest macroscopic life: stromatolites Cyanobacteria colonies sediments Produced billions of tons of O 2 Stromatolites Oxygen O 2 combined with iron No immediate increase in atmospheric O 2 Colonization of land: Ozone Layer Screens harmful UV radiation Ozone Function: First land plants 480 mya 3 Primates ~30 million years ago Pre-humans ~5-8 million years ago...
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Lecture 4 Water and Civilization - 1 Water, Life, Humans,...

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