Syllabus Edition

First teaching 2023

First exams 2025

|

Measuring Enzyme Activity (CIE AS Biology)

Revision Note

Test yourself
Cara Head

Author

Cara Head

Last updated

Measuring Enzyme Activity

  • The progress of enzyme-catalysed reactions can be investigated by:
    • Measuring the rate of formation of a product using catalase
    • Measuring the rate of disappearance of a substrate using amylase

Investigating catalase activity

  • In this investigation, the rate of product formation is used to measure the rate of an enzyme-controlled reaction:
    • Hydrogen peroxide is a common but toxic by-product of metabolism
    • This means it must be broken down quickly
    • Catalase is an enzyme found in the cells of most organisms that breaks hydrogen peroxide down into water and oxygen
    • Hydrogen peroxide and catalase are combined and the volume of oxygen generated is measured in a set time
    • The rate of reaction can then be calculated

Investigating Catalase Diagram

Catalase experiment, downloadable AS & A Level Biology revision notes

Experimental set-up for investigating the rate of formation of a product using catalase

Investigating amylase activity

  • In this investigation, the rate of substrate disappearance is used to compare rates of reaction under different conditions:
    • Amylase is a digestive enzyme that hydrolyses starch into maltose and glucose
    • Amylase functions best at pH 7 and 37oC (all enzymes operate best under specific optimal conditions)
    • Amylase and starch are combined and this reaction mixture is then tested for starch at regular time intervals
    • This can be done by taking samples from the reaction mixture at each time interval and adding each sample to someĀ iodine solution (starch forms a blue-black colour with this solution)
    • In this way, the time taken for starch to be broken down can be measured
    • The investigation can be repeated under a variety of conditions (e.g. by altering pH or temperature) and the reaction rates can then be compared

Investigating Amylase Reaction

Amylase experiment, downloadable AS & A Level Biology revision notes

Experimental set-up for investigating the rate of disappearance of a substrate using amylase

You've read 0 of your 10 free revision notes

Unlock more, it's free!

Join the 100,000+ Students that ā¤ļø Save My Exams

the (exam) results speak for themselves:

Did this page help you?

Cara Head

Author: Cara Head

Expertise: Biology

Cara graduated from the University of Exeter in 2005 with a degree in Biological Sciences. She has fifteen years of experience teaching the Sciences at KS3 to KS5, and Psychology at A-Level. Cara has taught in a range of secondary schools across the South West of England before joining the team at SME. Cara is passionate about Biology and creating resources that bring the subject alive and deepen students' understanding