2. 1.Sketch the ball and stick model of a water molecule and include the partial + and – charges. Illustrate with a dashed line a hydrogen bond between two water molecules. 2.Identify the emergent properties of water that are the result of water’s polarity and identify the importance of those properties to living organisms. 3.Describe adaptations that have evolved in populations of different species which employ the emergent properties of water.

3. Water’s polar nature results in a charge attraction between the hydrogens of one water molecule and the oxygen of another. Water molecules are bent, resulting in a lopsided placement of electrons. Thus, water molecules are polar. CH 2.5

4. Two molecules interacting weakly in one H bond, which can form and break easily H bonds are a part of other biologically important molecules as well. Many H bonds hold DNA’s two strands together along their length. Individually they are weak, but collectively stabilize DNA’s large structure. Fig. 2.9, p.27 Hydrogen Bonds

5. The Water Molecule is polar, but some things are not polar. Oil has no charges, is nonpolar and therefore hydrophobic Salt is ionic, has charges like water, and is therefore hydrophilic

6. Water’s polarity allows it to operate as a UNIVERSAL SOLVENT.

7. How does this allow for life to exist? Water’s Emergent Properties Universal Solvent Negative oxygen regions of polar water molecules are attracted to sodium cations (Na + ). + + + + Cl – – – – – Na + Positive hydrogen regions of water molecules cling to chloride anions (Cl – ). + + + + – – – – – – Na + Cl –

8. Many “salt” ions are important components of cellular processes. Sodium, Potassium, and Calcium are essential for muscle and nerve function.

9. Water molecules “stick” to each other, but while the molecules of water are attracted to each other, they can FLOW past each other while in their liquid state. Water’s Emergent Properties Cohesion and Adhesion Fig. 2.12, p.29 Fig. 2.10, p.28

10. The attractive forces between water molecules and nonwater surfaces give water the property called ADHESION. Water’s Emergent Properties Cohesion and Adhesion

11. Cohesion and adhesion, along with Evapotranspiration, work together to produce the phenomenon of Capillary Action. Water conducting cells 100 µ m

12. Cohesion and adhesion also work together to produce the phenomenon of Surface Tension. Water’s Emergent Properties Cohesion and Adhesion

13. Water has a high Specific Heat, which leads to a temperature stabilizing effect. Water’s Emergent Properties Moderation of Temperature

14. How have some animals evolved to employ water’s high specific heat and therefore high Heat of Vaporization? Water’s Emergent Properties Moderation of Temperature Heat of Vaporization

15. Water’s high Specific Heat helps give the earth a narrow temperature range from day to night and season to season. Water’s Emergent Properties Moderation of Temperature

16. The high specific heat gives water a high Heat of Vaporization which leads to Evaporative Cooling. (characteristic of life?) Water’s Emergent Properties Moderation of Temperature

17. As water cools and the molecules slow down, the hydrogen bonds become more established and the water molecules more organized. Therefore, ice is less dense than liquid water. Water’s Emergent Properties The Density Anomaly

18. How does this allow for life to exist? Water’s Emergent Properties The Density Anomaly

19. There is life under ice in the winter.