1. Chapter 3 Water & Biology

2. H 2 O is why we are here H 2 O molecules are polar What does their polarity contribute to? Each H 2 O molecule can form __ Hydrogen bonds?

4. Cohesion & Adhesion Caused by Hydrogen bonding Cohesion – Water-to-water Adhesion – water-to-something other than water When water travels upward in a straw, is that cohesion or adhesion? Why? Diameter of straw: small or large? Why?

5. Transpiration (Plants)

6. Structure & Function in water transport What structural feature of water enables it to be transported upward? Hydrogen bonding  Cohesion + Adhesion What structural feature of plant vessels enables water to be transported upward? Hydrophilic walls to enable adhesion Narrow walls to maximize adhesive forces

7. Surface Tension Surface Tension – water can stand above the rim of a glass due to hydrogen bonds Is surface tension a result of cohesion or adhesion? Why?

8. Water Moderates Temperature Temperature – measure of average kinetic energy of molecules Water does this because it has a high specific heat  Water can absorb large amounts of heat but change little in temperature  Guess what type of bonding is responsible for high specific heat?

9. Sea Breeze? (cranberry juice & …) Day, land heats up faster (low specific heat) Air over land rises Onshore breeze Night, lands cools faster Hot air rises over water Offshore breeze

10. Evaporative Cooling Water has high specific heat due to? Responsible for cooling Heat is released as liquid is vaporized into gas Highest energy molecules are vaporized first Vaporization involves the breaking of which bonds?

11. Hydrogen Bonding

12. Like dissolves like… Water is polar so it dissolves polar substances Also dissolves ionic solids (salts) Polar substances = hydrophilic » Hydro = water » -philic = to like(Dendrophiliac – one who likes trees) Water does not dissolve nonpolar substances NonPolar substances = hydrophobic » Hydro = water » -phobe = to fear (Triskaidekaphobe – one who fears the number 13)

13. Remember… Hydrophilic = polar molecule Will dissolve in water Hydrophobic = nonpolar molecule Will NOT dissolve in water What about ionic compounds?