Sec: Name: . ._ Experiment: Osmosis in Uving Cells (8. Science 10-7-3e) Purpose: To demonstrate turgor pressure in plant tissues, observe cells in various salt . concentrations, and determine if osmosis occurs in living cells. Materials: potato slices cucumber slices 3 - 250 ml beaker distilled water 15% NaGI .onion microscope glass slides cover glass dropper paper towel Methods: Part A: Turgidity in Plant Tissues 1. Place 50 mL of distilled water in one beaker and with the second add 50 mL of 15 % NaGI ~olution. Obtain 3 slices of potato and 3 slices of ~ucumber. Place one of the slices of potato in on Jeaker with distilled water and another slice in the )eaker with 15 % NaC/. Place a third potato slice m the desk. Place the cucumber slices the same .vay. Leave the dishes for about 1/2 an hour. z. ·ooseNe the fresh vegetables that had not been placed in any of the dishes. How would you describe their stiffness and texture? 3. Hemove some of the vegetables from the distilled water. How would you describe their stiffness and texture? 4. Has the turgidity of the cells in the distilled water increased or decreased? 5. \/Vhat conclusions can you draw from this observation? 6. Hemove some of the slices from 15 % salt solution. How would you describe their stiffness and texture? 7. Do these slices have greater or lesser turgidity than the slices that were not in any of the dishes? 8. Explain why the turgidity is the way it is with slices in the NaGI solution. Part B: Osmosis in Plant Cells 1. Cut a small piece of onion, remove the epidermis layer that is 1 cell thick. Prepar\1 8 wet mount (with tap water) of this & observe on high power. Draw observations. 2. Describe the position of the cell membrane and' the cell wall. 3. Place one drop of 15% NaGI solution at the edge of the cover glass. About every 30 seconds. add another drop of NaGI solution until you observe a change in appE~aranceof the cell. How many drops of NaCI were added before a change was noticed? 4. Do you think that water moved in or out of the cell? 5. VI/hy do you think this change occurred? 6. Draw the cell that you observed after NaGI was added. 7. Place a piece of paper towel at the edge of the cover glass and absorb as much of the salt solution as possible. Add distilled water at the edge of the cover glass, a drop at a time, watching the cells closely. Do you observe any changes in the cells? 8. Draw the cell that you observed after the distilled water was added.