Biology Lab Report

Submitted by Kezia Natania 9D

Aim: To find out how different factors could affect the rate of an enzyme catalyzed
reaction.
Research Question: How does different surface area affect the rate of an enzyme
catalyzed reaction?

Background Knowledge: The rate of a chemical reaction can be increased by having

more surface area of a particular solid reactant; this can be done by cutting the
substance into many small pieces. If the surface area of a solid reactant is increased,
more particles are exposed to the other reactant. The causes of a higher rate of
reaction is more particles are exposed to the other reactant, causing the small solid
particles to collide to each other faster and more frequently which raises the rate of
reaction.

Hypothesis: If the surface area of the solid is more ( cut into many small pieces ),
the rate of the reaction will be increased. Vice versa If the surface area of the solid is
less, then the rate of reaction will be less. This is a result of the particle size. With
more particles of the solid, the atoms can collide more frequently as there are more
particles to react with which speeds up the reaction as more particles are exposed to
the other reactant.

Apparatus:

Material Quantity Measurement

Potato 1 -
Scalpel 1 -
Cutti ng Tile 1 -
Test tubes 5 -
Hydrogen peroxide 5 portions 12ml each
Soap 1 1 drop each
Stopwatch 1 -
Ruler 1 15cm
Dropper 1 -
Syringe 1 12ml
Variables and Manipulation:
Variable Type of variable Manipulation
Temperature in the room Controlled variable All of the 5 containers are
placed next to each other
in the same room which
is the biology laboratory.
Volume of hydrogen Controlled variable All of the 5 tests tube
peroxide contain the same volume
of hydrogen peroxide,
which is 12ml.
Surface area of the Independent variable Since there are 5 test
potato tubes, each test tube
contains a different size
of potato. The
measurement follows:
1x1 potato, 2 div, 4 div, 8
div, and 16 div.
Amount of soap Controlled variable Each of the tests are
given 1 drop of soap.
Size of containers Controlled variable All of the experiment is
done using the same size
of test tube.
The height of the bubbles Dependent variable The reaction depends on
of each reaction the surface area and it is
increased by time.
Set-up diagram:

Test tubes

Hydrogen

potatoes
Method:
1. First, prepare all the materials needed for the experiment. Take 5 test tubes
of the same size. Don’t forget to label them.
2. Take a potato and start cutti ng it into its measurements. 1X1 , 2 divisions, 4
divisions, 8 divisions , 16 div.
3. Take the test tubes and fill all of them with the same amount of hydrogen
peroxide using the syringe which is 12ml.
4. Add a drop of soap to each of the test tubes.
5. Drop the each of the potatoes to the test tubes at the same time.
6. Lastly, start the stopwatch until 10 minutes and record the height of the
froth of each.

Results:

Raw data table

Number of divisions Height of froth (cm)

1 0.9
2 1.4
4 1.8
8 2.2
16 2.6

Processed data table

 Number of divisions Height of froth (cm) Rate of reaction (cm/min)
1 0.9 0.9/10=
0.09
2 1.4 1.4/10=
0.14
4 1.8 1.8/10=
0.18
8 2.2 2.2/10=
0.22
16 2.6 2.6/10=
0.26

Graph

Rate of reaction ( Height of Froth )

3

2.5

1.5

0.5

0
1 2 4 8 16

Height of froth

Discussion of Results:

I have conducted this biology experiment on 3 rd May 2018 on a Thursday. My

teammates were Clarissa, Jasmine, Ishanvi. Our subject teacher Ms. Liza gave us an
option to select a factor that affect the rate of an enzyme catalyzed reaction. Our
group finally chose surface area as our factor. Everyone brought their own fruits /
plant. For our group we chose potato as it is commonly used for these kind of
experiments. So we cut the potato into different divisions, and a total of 5 different
kind of surface area. We placed each division of potatoes in the test tube filled with
hydrogen peroxide and waited until 10 minutes with the stopwatch, as well as
observing the changes of the bubbles/ froth. For the first few minutes, I could
already see that the one with the highest froth was the one with the highest
number of potato divisions which has the largest surface area. The one with the 16
divisions had the highest froth, the lowest height of froth is the one which has 1x1
potato measurement, which has the smallest surface are compared to the rest of
the experiment.
It is also seen in the graph above, it forms a straight increasing line that goes
upwards, that shows that the froth kept on increasing with the increasing number
of surface area. From the results table, there are the raw data table and processed
data table. In the raw data table, I have organized the data in such a way that it is
easy to process. After 10 minutes is over, I took a 15cm ruler and measured the
height of each froth of the test tube and recorded the results. The results were as
follows( in an ascending order ): 0.9 cm, 1.4 cm, 1.8 cm, 2.2 cm, 2.6 cm. From 1-16
divisions of potatoes. We can agree that with the increasing surface area, the
height of the froth will also increase. Vice versa; with less surface area, the height
of the froth will decrease. This can be explain through the collision theory. With
increasing surface area, it means that the solid reactant is increased, having more
particles being exposed to the other reactant which is the hydrogen peroxide and
soap. With more small particles, it means that there are more molecules to collide
frequently with each other, which speeds up the catalyzed reaction altogether
compared to the solid particles which are less having smaller surface area; this
causes a slower reaction as it has less particles being exposed and to react with the
other reactants, which means less molecules to collide with each other, slowing the
catalyzed reaction. As one the reactants here is a solid ( the potato ), the surface
are affects how fast the reaction will go. The 2 types of molecules can collide into
each other at the liquid solid interface, i.e on the surface of the solid. The larger
the surface area of the solid, the faster the reaction will be. This theory greatly
matches with my results data and graph above.

Conclusion:
In conclusion, I can assert that my hypothesis is correct and valid as it matches
greatly with the results I have gotten from performing the experiment. In my
hypothesis I said that :
‘’ If the surface area of the solid is more ( cut into many small pieces ), the rate of
the reaction will be increased. Vice versa If the surface area of the solid is less, then
the rate of reaction will be less. This is a result of the particle size. With more
particles of the solid, the atoms can collide more frequently as there are more
particles to react with which speeds up the reaction as more particles are exposed to
the other reactant.’’
I can say that my results match with the hypothesis as I said in the hypothesis with
more surface area, the reaction will be increased, which means that the height of
the froth will be more. With less surface area, the reaction will be decreased, as a
result of particle size related to the collision theory. In my results, the one with the
highest froth is the one with the most number of divisions which has the largest
surface area, and the the one with the shortest froth is the one with the most least
number of division which is 1x1, which has the smallest surface area compared to
the other test. I can conclude that my hypothesis is accurate.

Improvement and Validity of Method :

N Method Strength Weakness Improvement

o
1 First, prepare all the It is smart to - When we did
materials needed for the prepare all the lab report,
experiment. Take 5 test the materials only 2 out of 4
tubes of the same size. to make sure of us were
Don’t forget to label them. the preparing the
experiment materials. If all
goes of us did it, it
smoothly. would save
more time.
2 Take a potato and start We cut it with With the ruler We should use
cutti ng it into its a scalpel and it was not a sharp scalpel
measurements. 1X1 , 2 a ruler to really and a metal
divisions, 4 divisions, 8 properly accurate as ruler next time
divisions, 16 divisions. measure it. we used a for more
plastic ruler. accurate
The scalpel measurements.
we used was
also not really
sharp.
3 Take the test tubes and fill We used the - -
all of them with the same same syringe
amount of hydrogen to pour the
peroxide using the syringe same volume
which is 12ml. of hydrogen
peroxide.
4 Add a drop of soap to each We used the It could have We can just
of the test tubes. same dropper been possible carefully place
and placed to drop more the soap.
the same than one drop
amount of of soap as it is
soap for each. easy to create
mistakes.
5 Drop the each of the It is important The potatoes One person
potatoes to the test tubes to drop them can be can just focus
at the same time. at the same dropped in dropping with
time to make the wrong one potato
sure the tube as measurement
reaction people have and making
started at the unsteady sure their
 same time. hand/ tube hands are close
not labelled to the tube so
correctly. it doesn’t fall
out.
6 Lastly, start the stopwatch It is good to - Focus on the
until 10 minutes and time the experiment
record the height of the experiment. and make sure
froth of each. to stop the
stopwatch at
10 minutes
sharp.

Bibliography:
Howard, John. “RATES OF REACTION - FACTORS.” HUMAN BIOLOGY / SMALL
INTESTINE - Pathwayz, 2015, www.pathwayz.org/Tree/Plain/RATES+OF+REACTION+-
+FACTORS.

Marie, Anne. “How Does an Increase in Surface Area Affect the Rate of a Chemical Reaction? |
Socratic.” Socratic.org, 2013, socratic.org/questions/how-does-an-increase-in-surface-area-affect-
the-rate-of-a-chemical-reaction.