Bio 220_Lab Exercise 3_Osmosis tonicity RBCs_F2020 (1).docx...

This preview shows page 1 - 3 out of 13 pages.

Lab Exercise 3 (Two Parts): Part 1: Determining Osmotic Concentration and Tonicity Part 2: Determining the Osmotic Concentration, Tonicity, and the Relative Effects of Different Solutions on Living Cells Virtual Lab Review the concept of osmosis in your textbook (Silverthorn 8 th ed p124-130; 7 th ed p125-132) & Solutions (Silverthorn 8 th & 7 th ed p42-43 or Figure 2.7), prior to coming to lab. Activities: 1. Complete the Lab Exercise 3 packet Complete all the sections including data fields that are within the lab packet. They are in red font. Watch the 3 videos as indicated in the lab. Complete the post-lab questions at the end of the lab. 2. Complete PhysioEX Exercise 1 Activity 3 Simulating Osmotic Pressure This activity will be demonstrated by the Instructor in the pre-lab introduction video. (Don’t worry if you don’t have PhsyioEx). 3. Upload finished packet through assignment link for grading. Objectives: Part 1: 1. Understand and apply the following terminology: osmotic concentration, osmotic pressure, osmotic equilibrium; penetrating solute (PS), non-penetrating solute (NPS) 2. When comparing 2 solutions separated by a semi-permeable membrane, be able to indicate their tonicity: hypertonic, hypotonic, isotonic 3. Apply your knowledge of osmosis and tonicity in physiological situations 4. Calculate osmotic concentration if given molar concentrations and the characteristics of the solute molecules involved 5. When comparing 2 solutions, be able to indicate their relative osmotic concentration (hypo, iso or hyper-osmotic); 6. Design a simple experiment that would test a given hypothesis related to osmosis and diffusion. Employ the steps to the scientific method in the experimental protocol. Part 2: 7. Observe changes that occur in living cells and be able to predict how the cell volume will change when placed into solutions of varying osmotic concentrations with variable tonicity. 8. Be able to use proper terminology to describe tonicity and osmotic concentration when comparing two solutions. 9. Employ the scientific method to test the following hypothesis: A living cell placed into a solution that is isotonic and hyperosmotic will not exhibit a net change in volume as measured by size when observed over time. Key Terms: Osmosis, selective permeability, hypertonic, hypotonic, isotonic, ICF, ISF, equilibrium, osmotic pressure, molarity, osmolality, ionic bonds, covalent bonds, hyperosmotic, hypoosmotic, isosmotic, hemolysis, osmometer, PS, NPS, crenation. Mitchem, F2020, page 1/13
Part 1: Determining Osmotic Concentration and Tonicity In last week’s experiment (Lab Exercise 2, Part 3) you demonstrated the processes of dialysis and osmosis across a non-living, semi-permeable membrane. You could tell that osmosis occurred because your dialysis bag gained weight. Osmosis is the net diffusion of water across a membrane . For osmosis to occur, the membrane must be 1) permeable to water, but 2) impermeable to some or all of the solutes; therefore, the membrane is considered semi- permeable (in living cells the term selectively permeable is used). When you have a

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture