Featured in PASCO’s College Biology Instructor Guide

College Biology Instructor Guide


College Instructor edition with 26 experiments covering introductory and general biology topics.

pH on Amylase Activity

Lab Summary

Use a water quality sensor and PASPORT colorimeter to measure the effects of pH on bacterial amylase activity.


In this activity, students investigate the concept that enzymes function within a range of pH. During the lab, students find the pH at which the enzyme bacterial amylase functions optimally. Students:

  • Observe the effects of bacterial amylase on a starch solution.
  • Explore the effects of pH on the rate of enzyme activity using six buffers of unknown pH.
  • Determine the optimal pH for bacterial amylase activity using qualitative and quantitative data.


Students will gain experience conducting the following procedures:

  • Use the colorimeter to test the effects of pH on bacterial amylase activity.
  • Use qualitative and quantitative data to find the optimal pH for bacterial amylase activity. pH will be varied using six buffers of unknown pH, varying from approximately 3.0 to 8.0.

Sensors / Equipment Used:

PASPORT Water Quality Sensor


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.

PASPORT Colorimeter Sensor


Our PASPORT Colorimeter records all 4 wavelengths simultaneously--no need to guess at wavelength to get a quality measurement.

Materials Used:

0.1 M Hydrochloric acid (HCl) solution - 30 mL
30% Starch solution - 30 mL
Bacterial Amylase solution - 4 mL
Cuvettes (with colorimeter) - 7
Disposable graduated pipets 
Distilled water - 200 mL
Graduated cylinder, 10-mL 
Lint-free tissue 
Lugol's Iodine (IKI) solution - 30 mL
Saltine cracker 
Six buffers of varying pH (pH 3.0, 4.0, 5.0, 6.0, 7.0 and 8.0) - 5 mL each
Small beakers or plastic cups - 19
Small funnel 
Standard buffer (pH 10) - 25 mL
Standard buffer (pH 4) - 25 mL
Wash bottle with distilled water

The Associated Bundle:

College Biology Bundle


A complete probeware bundle designed for PASCO's College Biology curriculum

Interface Required

This experiment may require software and an interface for data collection.