1. Pre lab Investigation question: What variables affect the passage of molecules through a cell membrane?

2. Part I Adding salt solution to Elodea- cellular level http://www.youtube.com/watch?v=VK- _YHakvho&feature=relatedhttp://www.youtube.com/watch?v=VK- _YHakvho&feature=related Adding distilled water – organism level of organism http://www.youtube.com/watch?v=H6N1IiJ Tmnchttp://www.youtube.com/watch?v=H6N1IiJ Tmnc

3. Propose at least two alternative hypotheses for your observations. (question 4). Submit one hypothesis via your student responder.

4. Some definitions to work with. Solute: a substance dissolved in a liquid Solvent: the dissolving medium in a solution. Concentration: the strength of a solution; number of molecules of a substance in a given volume.

5. Part II-dialysis model Molecule size investigation (2 students/group) Solute concentration investigation (2 students/group) Homework: plf