Laboratory Notes for BIO 1003
© 30 August 1999, John H. Wahlert & Mary Jean Holland
DIFFUSION AND OSMOSIS
Demonstrations on instructors bench:
- Demonstration 1. Materials: 250 ml graduated cylinder filled with tap water; potassium permanganate crystals, metal scoop for introducing them into cylinder.
- Demonstration 2: Materials: plastic thistle tube; 600 ml beaker of tap water; stand with clamp to hold inverted thistle tube; frog intesting, rehydrated (semipermeable membrane); rubber band; concentrated sugar solution (about 60%) colored with methylene blue for visibility. Setup: Fill bowl of thistle tube with concentrated solution, cover with frog intestine and affix with rubber band; invert thistle tube; hold with clamps on stand; partially submerge bowl of tub in tap water; mark stem at initial level of colored sugar solution; record change over time.
Glassware (setup at each of 6 stations):
- 6 balances (weigh up to 200.0 g), 1 at ech station
Solutions (setup at each of 6 stations):
- 9-inch finger bowls with distilled water
- 600 ml beakers containing distilled water and dialysis tubing
- 400 ml beakers (1 per group)
- microscope slides and cover slips
Organisms (two supply beakers per table):
- 1.0 liter stock bottle of distilled water for each of 6 groups
- 250 ml stock bottle of 15% sucrose
- 250 ml stock bottle of 30% sucrose
- 30 ml Wheaton dropper bottle of distilled water
- 30 ml Wheaton dropper bottle of spring water
- 30 ml Wheaton dropper bottle of concentrated salt solution (20% NaCl)
- 30 ml Wheaton dropper bottle of concentrated sugar solution (15% glucose)
- Elodea or Spirogyra in spring water
- dialysis tubing (1 inch flat) cut into 15 cm (approx. 7 in) pieces, soaking in distilled water in 600 ml beakers at each station
- lens tissue
- graph paper, 24 sheets per lab
- All cells live in a aqueous environment.
- Semipermeable membranes in organisms are chiefly phospholipid bilayers whose behavior is modeled by dialysis tubing.
- The interplay of concentrations across membranes creates problems that living cells and organisms must solve.
- Osmosis, Department of Physiology, University of Vermont
- Osmosis, Cell and Molecular Biology, Colorado State University
Return to Diffusion and Osmosis lab or Index.
Last updated 12 June 2006 (JHW)