BIOL 1201 Chapter : BIOL 1201 Take 2 Chapter 3
Document Summary
Water covers 70 percent of the earth"s surface. 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 billion years before it spread to land. All living organisms require water more than any other substance. Humans can survive weeks without food but no more than 1 week without water. 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. (i. e. polar molecules) or atoms that are charged (i. e. ions) Four emergent properties of water that contribute to earth"s fitness for life. 2. ability to moderate temperature: expansion upon freezing, versatile as a solvent. Cohesion- attraction between like molecules. (example: water molecules being held together by. Adhesion- attraction between unlike molecules. ( water molecules being held to cell walls by h bonds)
