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The Effect of Substrate Concentration on the Activity of the Enzyme Catalase

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The Effect of Substrate Concentration on the Activity of the Enzyme Catalase

Introduction

The aim of this investigation is to find out if changing the substrate
concentration will have any effect on the activity of the enzyme
activity.

Enzymes are a very important for all living things. This is because
they are essential to life as they are used in virtually every
metabolic reaction. They are designed to work within a temperature
range of 5-40ËšC, they do this as if it was any higher it would damage
living cells.

We call an enzyme a Biological Catalyst. A catalyst is a molecule
which speeds up a reaction. They are very important as if they were
not there reactions in cells would be to slow to support life.

They speed up reactions by lowering the activation energy needed in
the reaction. The activation energy is the energy needed to get a
reaction going e.g. activation energy is like pushing a rock to the
top of a hill and then pushing it off the top. The activation energy
is the energy needed to get the rock to the top of the hill. When it
is pushed of the top it no longer needs any help and it does it by
itself. The diagram below explains activation energy: -

Activation energy graph without enzyme

This graph show the energy with is needed to get a reaction going i.e.
activation energy.

[IMAGE]




[IMAGE]


Activation energy graph with enzyme

This graph shows what happens to activation energy when an enzyme is
added to the reaction. You can clearly see the difference and this
shows why enzymes speed up (catalyse) reactions.

[IMAGE]




There are two types of enzyme reaction, these are: -

* Anabolic - involved in synthesis

* Catabolic - involved in breakdown (yeast and hydrogen peroxide is
this type of reaction)

One amazing thing about an enzyme is that when it is used in a
reaction it will come out after the reaction exactly the same it was
when it went in.

All enzymes are globular proteins but not all globular proteins are
enzymes. They have a three dimensional structure with hydrophilic
R-groups arranged on the outside to ensure that the molecule is
soluble.

Enzymes are specific, this means that each enzyme will only work with
one reaction or one small group of reactions. This because each enzyme
has an active site this is a cleft in the enzyme surface where
substrate molecules can bind. The substrate molecule has to be the
correct shape for the enzymes active site or otherwise it will not
fit. This is the lock and key hypothesis. If the substrate does not
fit to the active site it tells you that it is not the specific enzyme
for the active site.

[IMAGE]


Fisher's lock and key hypothesis above (diagram from Biological
Science)

It is not enough for the substrate just to fit into an active site it
need an attractive force to keep it in place. The attractive forces
are

* Electrostatic attraction between oppositely charged groups

* Hydrogen bonding

* Permanent dipole-permanent dipole forces

* Instantaneous dipole-induced dipole forces

Once an enzyme molecule and a substrate molecule have joined together
it is called an enzyme/substrate complex.

In this investigation enzyme catalase accelerates the breakdown of
hydrogen peroxide into water and oxygen. This catalase-mediated
reaction is extremely important in the cells because it prevents the
hydrogen peroxide building up in the cells. Hydrogen peroxide is a
strong oxidizing agent which tends to disrupt the delicate balance of
cell chemistry.

The Plan

Variables

When you investigation enzyme activity there are several variables you
can change or modify, these are: -

* Temperature

* Ph level

* Substrate concentration

* Enzyme concentration

* Inhibitors

Temperature - this is where you would keep the same amount of
substrate and enzyme but change the temperature. You would have a
large range of temperatures (probably 10ËšC to 60ËšC). This is so you
can see when the enzyme is denaturized at 40Ëš and then see the enzyme
activity drop.

Ph level - this is where you would test the same amount of substrate
and enzyme but change the ph level. You would probably use a wide
range of ph levels to see how it behaves in an acid, neutral and an
alkaline solution.

Substrate concentration - this is where you would use change the
concentration of the substrate and keep the enzyme concentration the
same. Again you would want to use a wide range of concentrations so
you would get a wide range of result. Then from these you could draw
conclusions.

Enzyme concentration - this is basically the same as substrate
concentration but you keep substrate the same and change enzyme
concentration. As with substrate concentration you would want to use a
wide range of concentrations. This is so you would get a wide range of
results. In which you could draw conclusions.

Inhibitors - this is where you use the same enzyme and substrate
concentration but change the amount of inhibitors used. I.e. you could
have 0% inhibitors to 100% inhibitors. This would show you what affect
in inhibitors have on enzyme activity.

Catalase Enzymes

Catalase enzymes are enzymes which speed up reactions. Catalase
enzymes are some of the most potent catalysts known. The reactions it
catalyses are crucial to life. The catalase enzymes convert Hydrogen
Peroxide, a powerful and potentially harmful oxidizing agent into
water and oxygen. This is very important to life as if it did happen
your body would allow Hydrogen Peroxide to build up in the cells. This
would cause harm to your body. So the body has catalase enzymes which
break up Hydrogen Peroxide in oxygen and water. One example of a
Catalase enzyme is Yeast. Yeast is the catalase enzyme which is going
to be used in this investigation.

In this investigation it will look at how Substrate Concentration
affects enzyme activity.

What enzyme and substrate?

For the investigation the enzyme and substrate that will be used is
Hydrogen Peroxide and Yeast. Hydrogen is the substrate and yeast is
the enzyme. The formula for the reaction is:-



[IMAGE][IMAGE] Catalase Yeast added (enzyme)

Hydrogen Peroxide = Water + Oxygen



2H 2 O 2 = H 2 O + O 2



When hydrogen peroxide is left it will slowly decompose naturally into water and oxygen just from energy from the sun. This is why it is rarely kept in a clear bottle as it would otherwise decompose into water and oxygen. For this to happen it would take a very long time, this is why an enzyme was added. The enzyme acts as a catalyst and speeds up the reaction causing the water and oxygen to be released a lot quicker than it would take to naturally decompose.



The enzyme can speed up the reaction rate of the hydrogen peroxide because yeast enzyme fits the hydro peroxide active site. When the yeast binds with the substrate it creates an enzyme-substrate complex. The enzymes interaction with substrate causes it to break down into two product molecules (water and oxygen) leaving the yeast enzyme unchanged.



What must be kept the same?



To ensure that the investigation is reliable there are several steps which have to be taken to ensure this. These are:-

§ Keep enzyme concentration the same

§ Stir the yeast

§ Repeat test to increase reliability

§ Use same enzyme concentration in each test

Prediction

The reaction will start very quickly with as enzyme and substrate are
mixed. When the reaction starts bubbles of oxygen will be produced.
The largest volume of oxygen will be recorded in the first minute than
any other minute. This means the initial speed will be faster in the
first minute than any other minute. When substrate concentration is
increased the speed of the initial reaction will increase. This tells
us that substrate concentration is proportional to the initial rate
i.e. as substrate concentration increase the initial rate increases
and when initial rate increase substrate concentration increases. In
the later stages of the reaction the reaction will get slower and less
gas will be produced until in stop completely. This will be cause the
reaction not to be proportional any more.

This means the results which should be expected from the experiment
are

* Very high volumes of oxygen when there is a high substrate
concentration

* Then very low volumes of oxygen when there is low substrate
concentration

This will mean the curve on the graph will be steep at the beginning
where the reaction is at its fastest but as the reaction goes on it
will level off

The graph should look like this: -

[IMAGE]

Scientific knowledge can be used to explain why the above prediction
was correct. The initial reaction rate will be higher with a higher
substrate concentration and lower with a lower substrate
concentration. This is because at a higher substrate concentration
there will be more hydrogen peroxide (substrate) molecules available
to collide with the enzyme (yeast) active sites. This means at a lower
substrate concentration the rate of reaction will be lower because
there will be less substrate so it will take them longer to collide
with the enzymes active sites and bind with them.

Diagram to show this theory

High Substrate Concentration Low Substrate Concentration

[IMAGE]

[IMAGE]




[IMAGE][IMAGE][IMAGE][IMAGE]Enzyme

[IMAGE]

[IMAGE]

[IMAGE]

[IMAGE]

[IMAGE]

[IMAGE]

[IMAGE]

[IMAGE]




[IMAGE][IMAGE][IMAGE]Substrate

[IMAGE]

[IMAGE]

[IMAGE]

[IMAGE]

[IMAGE]

[IMAGE]

[IMAGE]

[IMAGE]




You can clearly see in this diagram how in high substrate
concentration collisions between enzyme and substrate molecules would
happen a lot quicker than in a low substrate concentration. As in a
high substrate concentration the substrate molecules out number the
enzyme molecules. While in a low substrate concentration enzymes would
out number substrate molecules.

The next part of the prediction is to explain why later on in the
reaction the rate of reaction will decrease while the substrate
concentration is still increasing. This happens because enzyme
concentration stays the same each time so there is only a certain
amount of active sites available at one time. This causes the enzyme
active site to become saturated. This means if there was 10 enzymes
active sites and 20 substrate molecules the first 10 substrate
molecules which collide will the 10 enzymes will be very quick, but
there will be 10 more substrate molecules left. These 10 molecules
will have to wait in a hypothetical queue until an active site is
free. This means the rate of reaction will be reduced. This will only
happen in the high substrate concentrations because it can only happen
when substrate molecules outnumber enzyme molecules.

Secondary written evidence to back up explanation

An explanation for the shape of the enzyme kinetics curve

At low substrate concentration the reaction rate increases sharply
with increasing substrate concentration because there abundant free
enzyme available (E) to bind added substrate. At high substrate
concentration, the reaction rate reaches a plateau as the enzyme
active sites become saturated with substrate (ES complex), and no free
enzyme to bind the added substrate. (BIOLOGY PROJECT
www.biology.arizona.edu)

[IMAGE]

What should the graph look like for initial rate?

[IMAGE]



Choices of equipment



In this investigation a number of different types of equipment are going to have to used to implement the experiment. The equipment needed is: -

· Gas syringe

· Delivery with needle for yeast insertion

· Digital stop watch

· Syringe



Gas Syringe - The Gas syringe has been chosen to be used to measure the oxygen given off in the reaction rather than other pieces of equipment which perform the same job. This choice was made because the gas syringe is a lot easily to operate than other option and you can clearly see the amounts of gas given off. This allows you to record the results quickly. Other options like counting the bubbles of gas are less reliable as you cannot be sure of the number of bubbles as they are too quick.



Delivery tube with needle for yeast insertion - This has been chosen as it reduces the chance of gas being lost. The yeast is inserted into the hydrogen peroxide with a needle through the bung. This allows there to be little amount of gas to be lost. This is unlike the other method which involves removing the bung inserting yeast and then putting the bung back on. This would cause there to be a high amount of gas lost. Using a delivery tube with a needle increases reliability and accuracy.



Digital stopwatch - This type of time measurement is used as it is very precise compared with a stopwatch which is analogue. Using digital stopwatch increases accuracy as it measures time more accurately than analogue stopwatches.



Syringe - Syringes are used to measure the quantities of yeast and hydrogen peroxide. This is because they can measure the quantities more accurately than pipettes can. Using a syringe allows you to measure out the different concentrations very accurately compared with using a pipette. This improves the reliability of the investigation if the quantities are measured more accurately.



Method



Apparatus



1. Gas syringe

2. Clamp stand

3. Tap water

4. Yeast enzyme

5. Hydrogen Peroxide substrate

6. Test Tubes

7. Beaker

8. Delivery tube with needle for yeast insertion

9. Digital Stop Watch

10. Syringe



Diagram



[IMAGE]


























Method

1. Arrange apparatus to how diagram shows

2. Check eye protection to ensure it is in place

3. Measure 60cm 3 of hydrogen peroxide and measure 60cm 3 of water. Mix them together to make 10% concentration hydrogen peroxide

4. Measure out the correct concentration which is to be tested (see table3)

5. Stir the yeast 5 times, then measure 2cm3 of yeast

6. Place the syringe in the holder on the bung on the test tube

7. Check gas syringe is fully compressed

8. Insert yeast into test tube and start stop clock

9. Keep a finger over the end of the syringe to ensure no air leaks out.

10. Record results in a table

Preliminary study to discover what quantities of enzyme and substrate
to use in my investigation

This preliminary study we help decide what quantities of enzyme and
substrate should be used in the investigation. The investigating is to
find what the effect of substrate concentration will have on the rate
of reaction. This means it should use about 5 different concentrations
of Hydrogen peroxide (the substrate). This will it will give a range
of results i.e. from a very strong concentration to a very weak
concentration. The 5 concentration which will be used in this
investigation are: -

* 20%

* 16%

* 12%

* 8%

* 4%

The next stage is to decide what the quantities of enzyme and
substrate should be. This is very important as if you get the
quantities wrong a number of things could happen: -

* reacts too quickly

* reacts too slowly

To ensure the right quantities are used in this investigation, a
number of different combinations of substrate/enzymes combinations
will have to be investigated to find the best combination. Below is
the first test:

Table to show results for test 1 of the preliminary study

Concentration (%)

Substrate Volume (cm3)

Water (cm3)

Yeast Volume (cm3)

20

10

0

4

15

7.5

2.5

4

10

5

5

4

5

2.5

7.5

4

2.5

1.75

7.5

4

Table 1

Results from test 1

The oxygen given off by the reaction filled the air syringe within the
3minutes (180secs). This may have been because the catalase quantity
was too high. This was reduced to 2cm3 for the next test and there was
a little difference in the results. For next stage volumes of
substrate were reduce and catalase volume was kept a 2cm3.

Table to show results for test 2 of the preliminary study

Concentration (%)

Substrate Volume (cm3)

Water (cm3)

Yeast Volume (cm3)

20

5

0

2

15

3.75

1.25

2

10

2.5

2.5

2

5

1.25

3.75

2

2.5

0.625

4.375

2

Table 2

Results from test 2

Once again the oxygen given off by the reaction was at such a large
volume that the gas syringe did not cope. These quantities were also
very difficult to measure, this meant mistakes could have easily been
made meaning the reliability would have been reduced. It was also
found to be very difficult to measure the substrate volume and water
volume to any high accuracy. This means these quantise are 'no' good.

This meant a rethink into the concentration of the substrates had to
be taken. It was decided that the concentration should be changed to:
-

* 10%

* 8%

* 6%

* 4%

* 2%

These concentrations were tested in test 3. In test 3 concentrations
were changed but catalase volume was kept a 2cm3. The 10%
concentration of the hydrogen peroxide (substrate) was made by
diluting the 20% hydrogen peroxide by added water to it i.e. adding 50
cm3 hydrogen peroxide to 50 cm3 of water.

Table to show results for test 3 of the preliminary study

Concentration (%)

Substrate Volume (cm3)

Water (cm3)

Yeast Volume (cm3)

10

20

0

2

8

16

4

2

6

12

8

2

4

8

12

2

2

4

16

2

Table 3

Results to test 3

This change to quantity's worked well with the gas syringe taking the
oxygen given off in the first 180sec in its measured space.

Bibliography

Web Sites used

An explanation for the shape of the enzyme kinetics curve -
www.biology.arizona.edu

Information on catalase - www.hamline.edu

Books used

Cambridge Advanced Sciences - Biology 1

Biological Sciences 1&2







Implementing



Safety issues



When working with chemical of any kind care has to be taken to ensure there are no accidents occur. This means you must implement safety procedures. The safety procedures which will be adopted when implementing the experiment: -

· Wear safety glasses to protect eyes from splashes of hydrogen peroxide

· All round care needs to be taken to avoid breakages of glass

· When throwing away chemical ensure they are thrown away correctly i.e. into a basin in a sink not in a bin or down the drain

· When clearly up breakages do not throw broken glass straight into bin. They have to be disposed correctly i.e. wrapped in paper of disposed in a bin dedicated to glass.



Risk Assessment



Risk

Chance of occurrence of risk (1-5)

Severity of risk (1-5)

Total Score (out of 25)

RISK FACTOR

Precautions

Splashes From Hydrogen Peroxide

4

2

8

Wear Safety Glasses to protect eyes

Spillages

2

2

4

Be careful not to spill solution and if there are any spillages clear up immediately.

Injuries from broken Glass

3

1

3

Clear up the glass following the procedures above.

Getting Hydrogen Peroxide in cut in skin

3

2

6

Wear plasters on cuts.



Precision of apparatus



The results of this investigation can only be good as the apparatus made available. The results can only be measured to the accuracy of the apparatus. The accuracy of the apparatus used in this investigation is: -



Gas Syringe - this can only measure to whole numbers i.e. 5cm 3 it cannot measure to decimals. This means the results have to be measured in whole numbers only.



Syringes - these can own be measure one decimal place i.e. 1.1cm 3 . This tells us that are measurement can only be accurate to one decimal place.



Stop Watch - these can measure in Hrs, Min and Sec so this investigation can only be accurate to this.



Table's of results



A table to show the results of the volume of oxygen given off as
Substrate concentration changes

Concentration of substrate (%)

Volume of oxygen given produced(cm3)

30sec

60sec

90sec

120sec

150sec

180sec

1

2

1

2

1

2

1

2

1

2

1

2

10

15

15

37

35

61

53

83

69

90

80

98

90

8

11

17

29

38

53

55

65

62

71

71

78

75

6

9

14

24

30

37

45

61

58

61

69

68

79

4

8

8

18

20

23

30

41

40

41

47

48

55

2

3

4

5

8

8

13

14

17

14

20

16

24

A table to show the average volume of oxygen given off as Substrate
concentration changes

Concentration of substrate (%)

Volume of oxygen given off (cm3)

30sec

60sec

90sec

120sec

150sec

180sec

10

15

36

57

76

85

94

8

14

34

54

63

71

77

6

12

27

41

55

65

74

4

8

19

27

38

44

52

2

3

7

11

14

17

20

Initial Rate

In this investigation an initial rate graph has to be shown to show
the difference in initial rate as concentration increases. It is used
to work out the initial rate at the beginning of the reaction so we
can compare the initial rates of all the concentrations to see if they
change.

Initial rate is worked out by calculating the slope closes to the
tangent to the curve, as close to 0 as possible. This means you
measure from just before the graph starts to curve.

e.g. The graph starts to curve on about 30 second. This means you take
30seconds. You then look on the graph to see the amount of gas
produced in this time. It says 2.7cm3 of oxygen. This mean 2.7 cm3 are
produced per 30sec. You then do a calculation of:-

Initial rate = Volume 2.7cm3

Time 30 = 0.09cm3/sec

A table to show the initial rate of the volume of oxygen given off as
substrate concentration changes

Concentration of hydrogen peroxide

2%

4%

6%

8%

10%

Initial rate (cm3/sec)

0.11

0.30

0.45

0.55

0.70

The graphs are labeled 1 to 6 for concentrations. See key below

* 10% = No.1

* 8% = No. 2

* 6% = No.3

* 4% = No. 4

* 2% = No. 5

* Initial rate graph = No.6



Analysing Evidence and drawing conclusions
==========================================

Analysing Evidence

In this section of the investigation it will present the data
collected in the appropriate forms. The section will include: -

§ Table of results

§ Table of averages

§ Table for initial rate

§ Graphs for each concentration 10%, 8%, 6%, 4% and 2%

§ An initial rate graph

Drawing Conclusions



If you look at the results you can see there is a very clear trend.
This is that as the concentration of substrate is increase the volume
of oxygen given off is increased. This can be shown by looking at
these figures. At 10% concentration 91cm3 of oxygen is given off while
at 2% concentration only 21cm3 is given off. This proves that at lower
concentrations of substrate is less volume of gas given off. While at
higher concentrations more oxygen is given off. This tells us that
there must be a relationship between substrate concentration and
volume of gas given off.



The amount of gas given of in the reaction decreases as it progresses. This is shown on the graphs by the line becoming more level late on in the experiment. The results for these experiments do not show it well but you can see the start of the volume of gas starting to decrease. The graph starts to level off for one main reason. The enzyme active sites are becoming saturated. This means that all the active site are being used and there is a queue of substrate waiting for the active site to come free. This means the rate of reaction is reduced causing the graph to level off.



You can see in the graphs for the higher concentration i.e. 10% and 8%. That there graphs have a steeper gradient at the start of the reactions compared with the lower gradients, which have gentler gradients. This may suggest that these have a faster reaction rate.



We can prove that initial rate is faster in the higher concentrations by looking at the graph for initial rate. This graph shows that as concentration is increased the initial rate will increase. There is some little evidence that the initial rate could be slowing down though at the higher concentration. This is because the differences between each initial rate are decreasing (except the last one which is an anomaly). This is telling us that the initial rate is getting close to its V max .



Compare with prediction



What my prediction states in a summary: -

1) When very high volumes of oxygen are produce it is a high substrate
concentration and when very low volumes of oxygen are produce it is a
low substrate concentration

2) As reaction progresses the volumes of oxygen will be reduced with
the graph levelling off.

3) Initial rate will increase but then level off as it reaches its Vmax.

(1)

You can see clearly on the graph that at high concentration i.e. 10%,
8% and 6% that the volume of is high. The volume of gas given off at
10% concentration after 180secs is 94cm3 if you compare this with the
2% concentration it is only 20 cm3.This happens because at the higher
concentration there are more substrate molecules than enzyme molecules
this means there can be more reactions = more gas produce. While in
the lower concentrations there are less substrate molecules. This
means that there can be fewer reactions than in the higher
concentrations causing a lower volume of gas to be produced. This
backs up the first bit of the prediction.

(2)

There is very little evidence that this has happened in these results.
There is evidence though that it is starting too happen and if the
timing had been extended for a few more minutes then maybe the graph
would show the oxygen levels decreasing and levelling off. The little
evidence that the results give is that as time goes on the difference
between each volume of gas decreases between each time interval i.e.
At 4% concentration

90sec

120sec

150sec

180sec

41

55

65

74

Difference between 90sec and 120sec = 14

" " 120sec and 150sec = 10

" " 150sec and 180sec = 9

There is a clear trend that as the rime goes on the defence reduces
thus suggesting it is slowing down. This then tell us that the line
must then level off. The line levels off as all the enzymes active
sites become saturated and causing the substrate molecules to queue
waiting for a free active site.

The results do support the prediction

(3)

Once again the results do not fully support the prediction as the
reaction was taken over a too short period of time. They do support
the first part of it; the initial rate does increase as the substrate
concentration is increased. This happens because in higher
concentration there are more substrate molecules available so the
reaction at the beginning very quick. Compared with lower
concentrations which have low initial rates as they react slow as
there are little substrate molecules available.

The graph does show the beginning of the initial rate reducing and
levelling off. The preceding initial rates do show that the reactions
are slowing down at higher concentration. This allows us to say that
if the test had been continued the graph would have levelled off. The
graph would have levelled off as all the active sites are used up so
they are saturated causing the rate to slow. The substrates could also
reached there vmax so they couldn't go any faster. This is backed up
by the prediction in most parts.



Compare with secondary data for initial rate graph



Hydrogen Peroxide Concentration

0%

4%

8%

10%

12%

16%

20%

Rate=30/Average (Cm3/second)

0

0.63

1.65

1.71

2.22

2.97

3.26



See graph no. 7



The secondary data does back up the results as the graphs look similar. These secondary results continue up to 20% concentration and you can see that the graph starts to level off unlike the graph for this investigation results.

































































































Evaluation

This section of the investigation will evaluate the investigation. It
will highlight areas of the investigation which went well, areas which
did not go so well as well stating ways of how the investigation could
be improved. I will comment on anomalous results, accuracy,
reliability and ways to improve the investigation.

Suitability of techniques

The techniques used in this investigation work reasonably well under
the conditions which they were performed in. If the investigation
could have taken place in Biology lab then there would have been more
accurate tools at disposal which would have made it more accurate. The
gas syringe worked well showing good results so there were no major
problems with the suitability of the techniques used.

Anomalous results

No experiment is ever perfect; if it was then there results would be
false. Every investigation has results which were wrong these are
called anomalous results. The anomalous results are shown below in the
table: - (The Yellow/blue cells are anomalous results)

Concentration of substrate (%)

Volume of oxygen given off (cm3)

30sec

60sec

90sec

120sec

150sec

180sec

1

2

3

1

2

3

1

2

3

1

2

3

1

2

3

1

2

3

10

15

15

n/a

37

35

n/a

61

53

n/a

83

69

n/a

90

80

n/a

98

90

n/a

8

11

17

n/a

29

38

n/a

53

55

n/a

65

62

n/a

71

71

n/a

78

75

n/a

6

9

14

n/a

24

30

n/a

37

45

n/a

61

58

n/a

61

69

n/a

68

79

n/a

4

8

8

n/a

18

20

n/a

23

30

n/a

41

40

n/a

41

47

n/a

48

55

n/a

2

3

4

n/a

5

8

n/a

8

13

n/a

14

17

n/a

14

20

n/a

16

24

n/a

The Cells in Grey - these cells are anomalous because they are a lower
concentration than the concentration above but they have given off a
higher volume of oxygen. The reason for this could have been that the
concentration was not correct i.e. too much/little water or substrate.
If it was not this it would have been because the yeast was not
stirred meaning that there might have been stronger solution yeast
than on the higher substrate concentration causing more gas to be
produced. They could have been also been caused by the gas syringe
sticking.

Main sources of error

Operator error is a main source of error in this investigation because
the operator may have misread the measurement on the gas syringe or
wrote down results wrong. They could also have mixed up concentrations
or may have put wrong concentrations in i.e. too much water etc. These
would all lead to the results being wrong and anomalous.

Design error is also a main source of error. This is because errors in
the design of the experiment could lead to there being anomalous
results. The main design errors of this investigation were that the
yeast was not stirred each time like it should have been done. This
has caused the yeast to have some areas which were high concentrations
of yeast and others which were low concentration yeast. This would
have led to there being some anomalous results. Other errors were
caused by operator errors and design error. Other design errors were
that the gas syringe did not run smoothly because it had no Vaseline
on it. This meant it got stuck some times causing anomalous results.

How have these errors affected results?

Errors will lead to anomalous results being caused. Below will explain
how the errors will affect the results.

When the yeast is not stirred it will cause there to be anomalous
result. The anomalous results will be fairly erratic. This is because
the yeast will have areas of it with different concentrations. This
means if the operator took a sample of yeast in a low concentration
the reaction would be slower while if they took it in an area of high
concentration it would have a fast reaction.

The gas syringe did not run smoothly this led to anomalous results.
This is because the syringe would stick on a certain measurement. You
would then record that measurement and as soon as you wrote it done
enough pressure builds up to unstuck it and it jumps to what it really
should be. This caused the results to be too low in places.

Improvements

Improvement could be made to the apparatus which would reduce errors
are: -

Gas syringe - this would be check before the experiment to ensure it
runs smoothly. This will allow it to give more accurate results as it
would not stick. This would be a good improvement as it would stop
results from being to low.

Yeast - this will be stirred before each experiment 15 times in future
experiments. This will ensure the solution is of the same
concentration each time and will prevent there from bring difference
in the concentration.

Organisation - organisation has to be improved in the future. This
would involve labelling test tubes to show there concentration. This
would avoid mix-ups between different concentrations. Also labelling
of the Hydrogen Peroxide and water would also help as these can be
easily mixed up. This will prevent mix up and allow results to be more
accurate.

Accuracy

The accuracy in this investigation was poor. This is because the
operator did not record the results well as they misread the gas
syringe on a number of occasions which led to anomalous results. This
has to be improved in any future experiment. This could be done by
always double checking the results to ensure they are correct.

The accuracy of the Gas Syringe was not very good as it could only be
accurate to whole numbers. It have done with being accurate to one
decimal place so that the results could have been more accurate as
with no decimal place is up to the operator to decide what the result
is. The reliability of the other pieces of the apparatus was good and
could not be improved.

Reliability

This investigation could have been more reliable but it was limited to
the resources of the school. This meant that only two sets of results
could have been taken. This reduced the reliability of the
investigation because the averages of two sets of results are not as
good as three sets. If the investigation was done again a minimum of 3
set would be taken. This would increase reliability of the results.
This would allow the results to be more valued so the analysis could
be proven.

Overall this investigation has gone well. The results would have been
better if 3 sets had been taken by the schools resources limited it to
only two. If the investigation was done again then the improvements
which were mentioned above would be implemented. This would improve
the overall results and make it the whole investigation more reliable.

How to Cite this Page

MLA Citation:
"The Effect of Substrate Concentration on the Activity of the Enzyme Catalase." 123HelpMe.com. 17 Apr 2014
    <http://www.123HelpMe.com/view.asp?id=121885>.




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