Chapter 3

Chapter 3 - Chapter 3 Water and the Fitness of the...

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Chapter 3 Water and the Fitness of the Environment Water: Hydrogen bonding, solubility and specific heat Cells are 70-95% water Water is the only common substance to exist on Earth in all 3 states of matter: solid, liquid, and gas. Life on Earth began in water and evolved there for 3 billon years before it spread to land All living organisms require water more than any other substance Human beings can go several weeks without food, but no more than one week without water. Concept 3.1 The polarity of water molecules results from hydrogen bonding The polarity of water molecules makes water a good solvent for molecules that have charged regions (i.e. polar molecules) or atoms that are charged (i.e. ions) Fig. 3-2 Concept 3.2 Four emergent properties of water that contribute to earth’s fitness for life 1. Cohesive behavior 2. Ability to moderate temperature 3. Expansion upon freezing 4. Versatility as a solvent Cohesive behavior : Cohesion- attraction between like molecules. Adhesion- attraction between unlike molecules. Fig. 3.3 Surface Tension o The force that allows the surface of a liquid to stretch without breaking o Due to the ordered arrangement of water molecules hydrogen-bonded to one another at the
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This note was uploaded on 05/10/2010 for the course BIOL 1201 taught by Professor Wishtichusen during the Summer '07 term at LSU.

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Chapter 3 - Chapter 3 Water and the Fitness of the...

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