Featured in PASCO’s College Biology Instructor Guide
College Instructor edition with 26 experiments covering introductory and general biology topics.
Diffusion and Osmosis
Use a water quality sensor to measure the changes in conductivity in two solutions separated by a semi permeable membrane.
The concept of transport across membranes is fundamental to understanding cell structure and function. In this lab, students investigate diffusion, osmosis, and facilitated diffusion using artificial membranes, tissue cores, and individual cells. Students:
- Investigate the processes of diffusion and osmosis in model membrane systems.
- Investigate the processes of osmosis in living plant tissue, and relate solute concentration to water potential.
- Use light microscopy to observe osmosis in living cells.
- Understand the concepts of diffusion and osmosis, and why they are important for understanding cell structure and function.
- Observe the effects of solute size and concentration gradients on diffusion across a semipermeable membrane.
Sample Lab - Diffusion and Osmosis (911 KB – PDF)
By performing this laboratory, students should be able to:
- Use a conductivity sensor to determine the relative size of water molecules, solutes, and membrane pores.
- Conceptualize molarity/solute concentration, and how it relates to osmotic potential of a solution.
- Use experimental evidence to determine the sucrose concentration of unknown solutions.
- Set up a controlled experiment to calculate the water potential of cells.
- Understand the importance of water potential, and how it relates to solute concentration and pressure potential within a cell.
- Use basic light microscopy skills to observe the effects of the movement of water into and out of plant cells.
- Understand the following concepts: tonicity, plasmolysis, crenation, tugor, and cell lysis.
Sensors / Equipment Used:
Measures temperature, conductivity, pH/ISE/ORP and dissolved oxygen. It is specifically designed for convenience in conducting water quality lab experiments. For use with PASPORT Interfaces.
1% starch solution - - 30 mL
15% NaCl solution 2 to 3 drops
2% IKI solution - 150 mL
2% IKI/2% NaCl solution - 150 mL
Beaker or cups, 30-mL - 6
Beaker, 250-mL - 2
Dental floss or string - 10 to 20 cm
Dialysis tubing - 180 cm
Disposable pipet - 5
Distilled water - 1 liter
Electronic Balance - 1 per class
Graduated cylinder, 25-mL
Knife - 1 per class
Labeling marker and tape
Potato - 3 to 4 per class
Red Onion - 1 per class
Roll of paper towels - 1 per class
Roll of plastic wrap - 1 per class
Sucrose solutions (0.2 M, 0.4 M, 0.6 M, 0.8 M and 1.0 M) - 35 mL each
The Associated Bundle:
A complete probeware bundle designed for PASCO's College Biology curriculum