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Purpose:
To allow each student to learn the properties of diffusion and osmosis and their roles in the transportation of materials across a semi permeable membrane. In addition, each student will observe the effect of solute concentration on water potential as it relates to living plant tissue. These tasks will be accomplished during a hands on laboratory investigation in which the students will collect data, graph their results, and use the information they obtained to answer questions.
Objectives Links:
Structure & Function of Cell Membranes
Process Skills Checklist
Materials:
Per lab group (3-4 students):
- 1 dialysis tubing (1@ x 12@)
- 350 mL distilled water
- 150 mL of 0.2 M sucrose
- 150 mL of 0.4 M sucrose
- 150 mL of 0.6 M sucrose
- 150 mL of 0.8 M sucrose
- 150 mL of 1.0 M sucrose
- cork borer
- plastic wrap
- potatoes
- thermometer
- several paper towels
- calculator
- triple beam balance
- test tape (for detection of glucose)
- IKI solution placed into dropper bottle
- 15 mL of 15% glucose/1% starch solution
- marking pencil and labels for marking beakers
- 10 pieces of string 8@ long for tying dialysis bags
- 6 plastic drinking cups (used as beakers)
The listed material amounts assume each lab group works with all six beakers and solutions. These amounts will be reduced if the different solutions are assigned to different groups of students.
Safety Concerns:
The teacher should review the following with all students taking part in this laboratory exercise:
- Since the students will be using IKI solution and test tapes during this laboratory exercise, the instructor should review basic safety precautions pertaining to the use of these chemicals.
- Instruct students to wear a lab apron and their safety goggles or glasses at all times during this laboratory exercise.
- Remind students that they should perform only the procedures described in the student directions and only under the supervision of the teacher.
- Remind students that should an accident occur during this laboratory exercise, the student should stop work immediately and notify the teacher.
Revision Date:
Summer 2001
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