Introduction to Cell & Molecular Biology (BIOL121) - Dr. S.G. Saupe (ssaupe@csbsju.edu); Biology Department, College of St. Benedict/St. John's University, Collegeville, MN 56321

Learning Activities - Water

 Objectives:  Upon completion of this unit you should be able to:

1. Provide some examples showing the importance of water in living systems.

2. Describe a water molecule.  Draw an electron dot structure for water.  

3. Explain why a water molecule is polar.

4. Define hydrogen bond.

5. Explain why water is critically important for life.
6. Discuss the significance of hydrogen bonds and the polarity of water for the properties of water.
7. Explain why "proton" is a synonym for "hydrogen ion"
8. Explain what is meant by pH and why it is important.
9. Compare and contrast acids and bases and provide examples of each.
10. Explain the significance/importance of buffers. 
11. Explain how the carbonic acid - bicarbonate buffer in the blood system works

12. Define electronegative and give an example of an electronegative atom.

13. Define cohesion and adhesion.  Give examples of each.

14. Compared to other similar sized molecules, such as ammonia, hydrogen sulfide, and carbon dioxide, water has unique properties.  Explain why.

15. For each of the following properties of water, define what is meant and give an example of the phenomenon especially how the property is biologically important:  (a) liquid at room temperature; (b) heat of vaporization; (c) specific heat; (d) heat of fusion; (e) surface tension; (f ) universal solvent; (g) density on crystallization; (h) compressibility; (i) transparency; (j) inert/reactiveness; (k) effect on shape of other molecules.

16. Define solvent and solute.  Give an example of each.

17. Identify the biological functions of water

18. Define xeric, mesic and hydric.  Give examples of adaptations of plants (and animals) to these conditions.

19. Define acid, base and neutral

20. Write the equation for the dissociation (ionization) of water, hydrochloric acid, sodium hydroxide, and carbonic acid.  Indicate which of these are acids, bases or neutral and explain why.

21. pH is defined as the negative log of the hydrogen ion concentration.  Explain what this means.

22. What is the concentration of protons in pure water?

23. Be able to complete the pH sheet given in class.

24. Define buffer.  Explain how the carbonic acid-bicarbonate buffer system works.

Concept Mapping:  
    Prepare a concept map using such such terms and concepts as:  water, hydrogen bond, polarized covalent bond, polar molecule, cohesion, adhesion, the properties of water, the functions of water, hydrophilic, hydrophobic, solvent, solute, hydrogen ion, proton, buffer, homeostasis, acid, base, hydronium ion, hydroxide ion.

Test Yourself:  Answer the questions at the end of the chapter in the text and/or study guide and/or textbook web site.

Reading:  
    Go to the library (or web) and read some articles about water.  Then discuss them with your friends.  Some possibilities include:

• L.J. Henderson.  1913.  Fitness of the Environment.  Macmillian, NY.

• Svitil, K.  1997.  Water World. Discover.  May. p 86.

Tape Recording Session:  
    Get a tape recorder and tape definitions of all the terms used in the chapter.  Use each in a sentence.  Play back the tape in your headphones as you cruise around campus.

Matching Question:
    The following is a list of some of the functions of water.  Match each to the property(s) that is associated with this function.  There may be more than one answer for some.