Cell Biology: Organisms and pH

Measure the buffering capacity of some biological materials in solution by comparing the ability of each sample to resist changes in pH when a strong acid or base is added. The sample solutions will be compared to negative (water) and positive (sodium phosphate buffer) controls.

Lab Summary:

In this exploration, students will use a pH sensor to study the effect of buffer solutions on pH. Students will measure the effects of acids and bases added to various biological substances (e.g. egg white, liver homogenate, and potato homogenate).

Download free labs:

(student versions)

Computer-based lab (PDF, 472 KB)

Xplorer GLX-based lab (PDF, 792 KB)

Method:

Use the pH Sensor to study the effect of buffer solutions on pH.

Here's What You Need:

Required for computer-based lab:

(See lab download for Xplorer GLX-based lab requirements, which may differ)

Probeware

• PASPORT pH Sensor (PS-2102)
• Xplorer GLX Graphing Datalogger (PS-2002)
  (or alternate PASPORT interface -- see other options)

Other Materials

• Beaker, 50-mL
• Graduated Cylinder, 100-mL
• Dropper bottles
• Wash bottle
• Waste container
• Water, 50.0 mL
• Liver Homogenate, 25.0 mL
• Potato Homogenate, 25.0 mL
• Egg White Solution, 25.0 mL
• Gelatin Solution, 25.0 mL
• Sodium Phosphate Buffer (Na2HPO4), 0.01 M, 25.0 mL
• Hydrochloric Acid (HCl), 0.1 M, 100.0 mL
• Sodium Hydroxide (NaOH), 0.1 M, 100.0 mL

Lab Manual:

The computer-based activity is included in Explorations in Biology (PS-2807). The Xplorer GLX-based lab is included in Biology with the Xplorer GLX (PS-2820). Both manuals are complete with Teacher Information pages, student instructions and handouts, and sample data.

For your convenience, we offer bundles which provide the probeware for the activities in the manual. For more, please see:
Computer-based Biology Lab Manual and Bundles
Xplorer GLX-based Biology Lab Manual and Bundles