Bean Juice (Amylase) Lab
Guiding Question: What affects the efficiency of bean amylase?
Materials:
small beakers, plastic syringes, hot plate, distilled water, dropper bottles with IKI, 1M
Hydrochloric Acid- located on the front table, bean juice (water that dried beans
soaked in overnight), starch solution
Your Goal:
As a group select one of the following variables to explore what affects the efficiency of
amylase.
 Concentration of enzyme/starch solution
 Temperature of starch solution
 pH of starch solution
Once your group has selected your variable, select two of the following four beans to
compare. You will test your selected variable on the two types of beans you pick!
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Pinto Beans
Kidney Beans
Black Beans
Lentils
Hypothesis:
You should create two hypotheses, one for each type of bean tested. Each hypothesis
should include what you believe will happen to the rate of the enzyme activity.
Procedure:
1. Measure out 10 ml of the starch solution and place in a beaker.
2. Add 1 drop of IKI to the beaker. Note color change in
your journal under observations.
3. Fill a different syringe with bean juice. Add one drop at a time of bean juice to the
starch-IKI solution until the solution clears. Note how many milliliters it takes to
clear the solution.
4. Record your response in the appropriate chart on your data charts handout.
5. Repeat the following steps, altering the variable.
Variable Procedures
When testing Concentration of Starch Solution (all groups):
 Add 5 ml of starch solution plus 5 ml of distilled water to the beaker. Repeat
steps 2-4.
For those groups Heating/Cooling:
 Add 10 ml of starch, BEFORE ADDING IKI, put your beaker on the hot plate
set to the lowest temperature. Heat only until steam starts to form. Remove the
beaker from the hot plate. Repeat steps 2-4.
 Obtain 10 ml of starch from the front of the room that is in the ice bucket, note
the temperature of the thermometer (add to observation section!). Add this
starch to a clean beaker. Repeat steps 2-4.
For those groups adding Acid/Base:
 Add 10 ml of starch to a clean beaker, BEFORE ADDING IKI, add 1 drop of 1M
HCl (hydrochloric acid) to the starch solution. Repeat steps 2-4.
 Add 10 ml of starch to a clean beaker, BEFORE ADDING IKI, add 1 drop of 1M
Sodium Hydroxide (NaOH) to the starch solution. Repeat steps 2-4.
For those testing Concentration of Enzyme/Starch Solution
 Add 5 ml of starch solution plus 5 ml of distilled water to a clean beaker. Repeat
steps 2-4.
 Add 10 ml of starch solution to a clean beaker. Add 1 drop of IKI. In a separate
beaker, a 5 ml of enzyme and 5 ml of distilled water and mix (by stirring). This
creates a diluted enzyme concentration. Repeat steps 3 & 4.
Pre-Lab Questions (ANSWER AS PART OF YOUR PRELAB!):
1. What is the independent variable in this experiment?
2. What is the dependent variable in this experiment?
Post Lab Observation Questions:
REMINDER: Be sure to write in complete sentences with complete explanations! Reword the question in
the answer. Do not use 1st person (any “personal” language- I, we, they, you, etc!)
1. What evidence do you have that bean juice is an enzyme?
2. What was the purpose of the IKI?
3. How did adding acid to the starch solution affect the amount of bean juice that was
used? How did adding base to the starch solution affect the amount of bean juice
that was used? Explain.
4. What did heating the solution while adding the bean juice show? What did cooling
the solution while adding the bean juice show? Explain.
5. What happened when the starch solution was diluted with DI water (the
concentration was changed)? Explain.
6. Were there any major differences in the amylase (meaning did it matter if the
amylase came from the pinto beans, kidney beans, black beans, or lentils)?
*Remember, when you are answering questions 3-5, discuss results FOR EACH TYPE OF BEAN
TESTED.
Conclusion:
Follow the Power Conclusion format.
Questions to consider when writing the WHY did you get the results that you did
section of the Power Conclusion:
1. What can you infer about amylase from the data? Why? (What conditions does it
work best under? What conditions hinder it the most?)
2. Where in the human body is amylase typically found? What are its ideal
conditions?
3. Do the conditions that you found the amylase to work best under correlate with
the function of amylase in the human body?