IA ON BIOCHEMISTRY – YOUR RESOURCE CENTRE
WHERE SHOULD I BEGIN?
This resource sheet is NOT an exhaustive guide to the many types of experiments you may
want to do for your next IA. Rather, it should allow you to ‘make a start’ in your quest to design
and complete your next Official IB Biology experimental project.
Remember that your IA’s are worth a whopping 25% of your overall IB Biology Grade.
Furthermore, they need a huge investment of your time and of class time.
If this IA goes well, you will have one good Design, DCP and CE to submit to the IB. Remember
that you only need submit 2 of each!
This file contains a collection of ideas for experiments, experimental protocols and resources
relating to experiments you might light to conduct relating to the IB Biochemistry content.
Try to choose which experiment you want to work on and let me know by this Friday (Feb 15 th).
That way, I can be sure to have all of the resources you need once you are back form academic
travel.
You can, of course, come up with your own ideas and your own experiment, You should
DEFINITELY customize any protocol you learn about here to make it unique, and your own.
It is a GREAT idea to work with a partner or a couple of colleagues. You can act as assistants for
each other as you run your experiments, and share background resources. For example, one of
you may choose to examine the effect of pH change on enzyme activity measured in a specific
way, while another may choose to investigate the effect of changing substrate concentration
on the same enzyme activity measured using the same method….
I AM HERE TO HELP YOU. I WANT TO HELP YOU! I WANT YOU TO HAVE FUN DOING YOUR
EXPERIMENT! So please consult me! I know that this is hard, and I want to help in any way I
can!
Your first decision is whether you want to do an investigation into the biologically important
chemical
properties
of
water
(Specific heat capacity, freezing point, specific heat of vaporization etc etc) OR an investigation
of aspects of enzyme function.
Remember, enzyme activity can be affected by a number of factors, including
1. Temperature
2. pH
3. Substrate concentration
4. Enzyme concentration
5. Presence or absence of inhibitors
There is a GREAT web resource reviewing these factors (which you can quote as a source) from
Worthington Biochemistry here.
LACTASE
Ideas:
1. How does pH change affect lactase activity?
2. How does temperature change affect lactase activity?
3. How does substrate concentration affect lactase activity?
4. End-product inhibition of lactase activity
1. This is a fantastic teaching resource with a whole collection of ideas for lactase enzyme
labs
2.
This is a great Vernier probe lab which uses CO2 production by yeast as the means of
testing for lactase enzyme activity. Unusual and interesting…
3. This is a simple protocol to look at the effect of heat on lactase enzyme activity. You
could adapt it to look at other factors such as substrate concentration, pH, etc…
4.
This link will give you useful background information about optimal temperature and
pH for lactase, as well as ideas for investigating end-product inhibition on lactase
efficacy.
5.
More background information about lactase
PEPSIN
Here is a link giving you fine detail about pepsin…
1. An overview to the use of a Vernier Colorimeter to investigate factors which influence the
efficacy of pepsin for breakdown of protein.
2. An interesting investigation which looks at the efficacy of antacids (mediation used to treat
indigestion), and their effects on pepsin activity
CATALASE
1. Vernier probe lab that measures catalase activity using a gas pressure sensor. This comes
complete with a useful video!
2. A Vernier lab that measures catalase enzyme activity using an oxygen pressure sensor.
3. A really useful lab, including a simulation to help you gain confidence, looking at the effects
of temperature on catalase activity, using an acid/base titration method. It can easily be
altered to allow you to look at pH, substrate concentration, enzyme concentration or
inhibitor effects!
4. A lab protocol which uses filter paper discs soaked in catalase to measure the effects of pH
or temperature change on catalase activity
5. A lab protocol that investigates the effect of an enzyme inhibitor, copper, on catalase
activity using the filter paper method
AMYLASE
Amylase is an enzyme that catalyses the hydrolysis of starch. Iodine and starch react to
produce a blue-black colour, so that iodine can be used to show the rate of starch breakdown by
amylase. A light probe or colorimeter can be used to indicate the change in optical density as
the iodine solution changes colour.
1. A brief introduction to the use of colorimetry to measure starch breakdown by amylase
2. A simple ‘practical’ experiment that could be adapted to use proprietary amylase and the
starch source of your choice!
CHEMICAL PROPERTIES OF WATER
1. A link from Penn State University, describing one method to evaluate and compare the
specific heat capacity of distilled water compared with other solvents or liquids (for example,
salt water).
A collection of Vernier Labs which investigate the freezing properties of water and compare
with other solvents or liquids (for example, varying degrees of salinity)
1. Vernier 1
2. Vernier 2: Freezing of ocean water
3. Vernier 3: Effects of temperature on the solubility of oxygen in water
4. A great NASA link to the a collection of experiments which investigate effects of salinity on
the water cycle – evaporation, specific heat capacity, etc etc.
5. A link to a very simple experiment investigating the effect of salinity on the heat of
vaporization of water