IB Biology
IA DESIGN LAB: ENZYME ACTIVITY
There are various factors that can affect enzyme activity. Depending on the enzyme, it can be
very sensitive to one particular factor but not another.
You will design an investigation to test some factor that affects enzyme activity.
Possible Factors:
a. temperature
b. pH
c. concentration of enzyme
d. concentration of substrate
e. other (your choice)
Possible enzymes to study:
Catalase
Catalase is an enzyme found in living organisms and will break down the H 2O2 to water and
oxygen gas. Sources of catalase include liver, potato, yeast, carrots, and apple. Rate of
enzyme activity may be determined by using a gas-pressure probe, collecting the gas
produced, or the assay of the time it takes a filter disc coated with enzyme to rise to the
surface of a test tube.
Lactase:
Lactase found in dairy products breaks down lactose to glucose and galactose.
The level of glucose can be measured using glucose test strips or using the Benedicts test.
Individuals who are lactose intolerant must avoid dairy products or take the enzyme in pill form
(Lactaid).
Amylase:
Amylase brakes down amylose (starch) to maltose. Iodine is used to indicate the level of
starch and glucose test strips or the Benedicts test can be used to determine the level of
glucose.
Bromelain:
Bromelain is a proteolytic enzyme (hydrolyzes protein in gelatin) that is found in pineapple,
papaya, and kiwi.
Catechol oxidase (catecholase)
When some fruits are cut open the surface exposed to oxygen turns brown. This happens in a
two stage process: catechol is converted to a yellow pigment by the enzyme. The yellow
pigment reacts with oxygen to become the brown pigment, benzoquinone.