Practical: The Effect of the Enzyme Catalase from Chicken Livers on Hydrogen Peroxide
Strand1: SA1, SA2, SA3
Date:
Group Members:
Marks:
/12 (Part A)
+
/18 (Part B)
=
/30
INTRODUCTION:
There are many different reactions that are happening in our bodies all the time. There are
reactions that build up molecules, synthesis/anabolic reactions, as well as reactions that
break down molecules, catabolic reactions. Together the sum of all anabolic and catabolic
reactions in our bodies makes up our metabolism.
Enzymes are proteins that speed up the rate of reactions that would otherwise happen
more slowly. The enzyme is not altered by the reaction and so has the ability to work again
and again. You have hundreds of different enzymes in each of your cells that perform
hundreds of different functions; however each enzyme is specific for one particular reaction.
All enzymes function best at a specific temperature and pH, we call this its ‘optimal’
temperature and pH.
In this practical, you will study an enzyme that is found in the cells of many living tissues
called catalase (KAT-uh-LAYSS). It speeds up a reaction which breaks down hydrogen
peroxide, a potentially toxic chemical, into 2 harmless substances, namely, water and
oxygen.
This chemical reaction is written as follows: 2H2O2 → 2H2O + O2
You will be looking specifically at the catalase found in chicken liver and conduct an
investigation on the effect of temperature on its activity.
INSTRUCTIONS:
 Work in groups of 2 or 3.
 Follow the practical procedure (Part A) and then the investigation (Part B) and finally
answer the questions that follow.
 Each group member will need to record all answers as they will be needed to answer
the individual questions in the next period.
1
MATERIALS:
3 X 10ml Graduated cylinders
Measuring pipette
20Vol (6%) Hydrogen peroxide solution
Sharp knife (scalpel)
Forceps (tweezers)
Electronic scale
Chicken liver at room temperature
Boiled chicken liver
Frozen chicken liver
Stirring rod
PART A – Practical Procedure: Catalase activity from chicken livers at room temperature on
hydrogen peroxide.
AIM: To determine the effect of catalase in chicken livers, at room temperature, on
hydrogen peroxide and to test the products from this reaction for the presence of oxygen.
Room Temperature Catalase Reaction Method:
1. Place 1 ml of the 6% hydrogen peroxide solution into a clean 10ml graduated
cylinder.
2. Using forceps and sharp knife/scalpel cut 0.1g of chicken liver (this is approximately
half the size of a 10c coin) and add it to the measuring cylinder
3. Label measuring cylinder 1 – ‘Control’
4. Push the piece of liver into the hydrogen peroxide with a stirring rod. Observe what
happens.
5. Leave the reaction for 4 minutes and then measure how high the bubbles rose.
6. Conduct a simple test for oxygen (O2) by placing a glowing splint into the bubbles.
(PRECAUTION: Oxygen is highly reactive. Make sure that you have blown out the
splint so that it is only a glowing ember before placing it into the test-tube).
QUESTIONS:
1. What was the volume of bubbles in measuring cylinder 1?
(1)
2. What is the test for oxygen?
(1)
3. What did you observe when you put the glowing splint into the test-tube filled with
bubbles?
(2)
4. What is the effect of catalase on hydrogen peroxide?
(1)
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PART B – Practical Investigation: The effect of high and low temperatures on catalase
activity on hydrogen peroxide.
AIM: To determine the effect of temperature of catalase, from boiled or frozen chicken
livers, on hydrogen peroxide.
Boiled Liver and Frozen Liver Catalase Reaction Method:
1. Place 1 ml of 6% hydrogen peroxide solution into 2 separate clean 10ml graduated
cylinders.
2. Label measuring cylinders 2 – ‘boiled liver’ and 3 – ‘frozen liver’.
3. Using forceps and a sharp knife/scalpel cut 0.1g of previously boiled and then 0.1g of
previously frozen chicken livers. (Note: this needs to be done quickly as the liver may
defrost).
4. Add the boiled liver into measuring cylinder 2 and the frozen liver to measuring
cylinder 3.
5. Push the liver down into the measuring cylinder using a stirring rod.
6. Leave the reaction for 4 minutes and then measure how high the bubbles rose in
each measuring cylinder.
RESULTS:
1. What was the volume of the bubbles in:
a) Measuring cylinder 2?
(1)
b) Measuring cylinder 3?
(1)
Group mark:
2 = excellent work
1= could be better
0 – not done
Group worked quietly and well together with very little help
from the teacher
Group cleaned up the area without being reminded to do so
and asked teacher to check the area was clean
Worksheet neatly filled in and handed in at end of lesson,
together with all group members’ sheets.
/1
/5
PART A TOTAL = 12 MARKS
3
INDIVIDUAL WORK
Name:
QUESTIONS:
1. Suggest REASONS for the differences you saw between the 3 measuring cylinders in
terms of rate of reaction and temperature.
(3)
2. List TWO things that needed to be kept the same (fixed variables) in this
investigation.
(2)
3. Identify the independent and dependent variables in this investigation.
a) Independent variable:
(1)
b) Dependent variable:
(1)
4
4. State a Hypothesis for this investigation.
(3)
5. Give a conclusion to this investigation.
(3)
6. Describe the reaction and how you measured reaction rate. Is this method very
accurate? Explain your answer.
(4)
5
7. Suggest at least one way in which you can apply knowledge gained about enzymes by
doing this investigation to a real world situation.
(1)
PART B TOTAL = 18
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