SCB 115 Lab 5 Diffusion and Osmosis

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Exercise 9 Content

Learning Objectives

After completing this lab, the students will be able to:

  • define diffusion and osmosis.
  • explain the relationship between rate of diffusion and molecular weight
  • Predict the movement of water (or other substances) across semi-pemeable membranes.
  • Recognize hypertonic, hypotonic and isotonic solutions.
  • Predict changes in living cells placed in a hypertonic, hypotonic, or isotonic solution.

Lab Readings

Read the following materials before you begin the experiment.

  1. 5.2: Passive Transport contributed by Boundless (Libretext).
    5.2A: The Role of Passive Transport
    5.2B: Selective Permeability
    5.2C: Diffusion
    5.2D: Facilitated transport
    5.2E: Osmosis
    5.2F: Tonicity
  2. Passive Transport: Filtration and Facilitated Diffusion by Barbara Liang.
    Click Next to start the slide.
    Passive transport: osmosis by Barbara Liang.
  3. Chapter 7-3 The Cell Membrane; Active and Passive transport (21 slides).
  4. by Anupama Sapkota.
  5. Passive transport, active transport, Bulk transport (Openstax).
  6. Active transport: Endocytosis, Exocytosis, and Sodium-potassium pump.


  1. View Transport Across Cell Membranes video below or on YouTube, before you start the lab activity.
  2. View active transport.wmv on youTube.

Lab Activity

in this lab activities, you will observe how to conduct these experiments in the lab.

  1. Diffusion Methylene blue through Agar Gel. 
  2. Diffusion Potassium Permanganate, Methylene Blue, and Safranin after 30 minute.
Diffusion Potassium permanganate and Methylene Blue through agar gel after 1 hour.

3. Cell membrane model demonstration using dialysis tubing on you tube.
4. Dialysis Tubing Diffusion Time-lapse on you tube.
5. Osmosis Demo. Time lapse start at 3.50. (Bozeman Science)
6. Onion Osmosis happened after salt solution is added.

7. Red blood cells under the microscope, hypo and hypertonic solutions.


  1. Diffusion Quiz (6 questions)
  2. Cell transport quiz.