This chapter describes the structure of the water molecule and explores the many ways that polar covalent bonds and hydrogen bonds among water molecules affect organisms and their interactions with their environments. In addition, this chapter discusses topics including concentrations of solutions, hydrogen ion concentration (pH), and buffer solutions. | Lecture Biology (7th edition) - Chapter 3: Water and the fitness of the environment Chapter 3 Water and the Fitness of the Environment PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Overview: The Molecule That Supports All of Life – Water is the biological medium here on Earth – All living organisms require water more than any other substance Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Three-quarters of the Earth’s surface is submerged in water • The abundance of water is the main reason the Earth is habitable Figure Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Concept : The polarity of water molecules results in hydrogen bonding • The water molecule is a polar molecule Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • The polarity of water molecules – Allows them to form hydrogen bonds with each other – Contributes to the various properties water exhibits – + Hydrogen H bonds + – H – + + – Figure Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Concept : Four emergent properties of water contribute to Earth’s fitness for life Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Cohesion • Water molecules exhibit cohesion • Cohesion – Is the bonding of a high percentage of the molecules to neighboring molecules – Is due to hydrogen bonding Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Cohesion – Helps pull water up through the microscopic vessels of plants Water conducting cells Figure 100 µm Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings • Surface tension – Is a measure of how hard it is to break the surface of a .
