BIO152H5 Lecture Notes - Lecture 2: Dehydration Reaction, Cn Tower, Disaccharide
Document Summary
Life on earth began in water and evolved for 3 billion years. Water is important for chemical reactions because water is often the one thing that allows certain molecules to form together or break apart. Evaporation from leaves pulls water upward from the roots through water-conducting cells. Because of the properties of cohesion and adhesion, the tallest trees can support water more than 100m upward-approximately one-fifth the height of the cn tower. Water molecules are attracted to one another and bonded to one another. Cohesion due to hydrogen bonds between water molecules helps hold together the column of water within the cells. Adhesion of water to cell walls by hydrogen bonds helps resist the downward pull of gravity. Cohesion and adhesion together explain how water transports from roots to leaves. Surface tension is a measurement of how difficult it is to break the surface of water.
