LOGBOOK FOR SCIENTIFIC
INVESTIGATION
Yr 12 Biology Unit 3 and 4 (2025)
Thien-An Le
,Table of Contents
Contents
Table of Contents................................................................................................................... 1
Introduction and Preface ........................................................................................................ 2
Deciding on the topic ............................................................................................................. 3
Background Research ............................................................................................................ 5
Experiment Design ................................................................................................................. 8
Research Topic .................................................................................................................... 18
Experiment .......................................................................................................................... 20
Results and Observations: ................................................................................................... 22
Discussion .......................................................................................................................... 28
Summary/Analysis of Results............................................................................................ 28
Potential Extraneous Variables and Limitations in Method ................................................. 29
Further Research .............................................................................................................. 30
Conclusion .......................................................................................................................... 32
Acknowledgements ............................................................................................................. 33
1|P age
,Introduction and Preface
23/04/2025
The purpose of this logbook is to provide a basis for further learning in future studies. This
logbook will include my planning, thinking process, observations, data, research, and
conclusions.
The goal of my experiment is to formulate a scientific investigation that relates to the content
covered in VCE Biology Units 3 & 4. My partner (Nethaya) and I will conduct the experiment at
our school, Christway College, and the formation of my research and results will be done both
at school and at home.
This experiment aims to investigate the viscosity of jelly and how different concentrations of
enzyme will affect the viscosity of the jelly. Viscosity is a measure of a fluid’s resistance to
flow1. A fluid with a high viscosity will resist motion, while a fluid with a low viscosity will flow
more easily with little friction when in motion. When the jelly is set, the viscosity of the jelly is
said to be high, while when the jelly is not set, the viscosity of the jelly will be low. Enzymes are
organic molecules, typically proteins that catalyse (speed up) specific reactions.2 Enzyme
concentration refers to the amount of an enzyme that is present in a specific space. As the
enzyme concentration increases, the rate of the chemical reaction will increase as more
enzymes are able to bind to substrates and carry out the chemical reaction.
In the following experiment, the enzyme involved is bromelain, which is a digestive enzyme, that
is found in pineapple juice. For this investigation, the concentration of the pineapple juice and
the bromelain is said to be the same (for example 50% concentration pineapple juice=50%
bromelain enzyme). However, realistically, the concentration of the bromelain enzyme will
defer in the pineapple juice. One study found that in a 100% concentration pineapple juice, the
concentration of bromelain enzyme was said to be 0.43%3.
Furthermore, an important protein involved in this investigation
is gelatine. Gelatine is the substrate to the bromelain enzyme,
and when they bind together, the gelatine is digested by the
bromelain enzyme. Gelatine is a protein that is derived from
collagen and plays a significant role in jelly setting. In jelly, the
gelatine forms a complex matrix, which traps water between its
coils and nets, causing the jelly to become set and jiggly (figure
1).
When bromelain and gelatine is added together, the bromelain
digest the gelatine, thus there is insufficient gelatine available
for the jelly to set, therefore the viscosity of the jelly is low.
Figure 1 Coils and nets in gelatine
However, when bromelain and gelatine is not added together,
structure (matrix)
the bromelain does not digest the gelatine, and thus there is
enough gelatine available for the jelly to set, therefore the viscosity of the jelly is high.
1
https://www.princeton.edu/~gasdyn/Research/T-C_Research_Folder/Viscosity_def.html
2
Edrolo Textbook Ch.3
3
https://www.jstage.jst.go.jp/article/chikusan/88/3/88_335/_article/-
char/en#:~:text=Applying%20the%20load%20of%20gumminess,the%20pineapple%20juice%20was%20
0.43%25.
2|P age
, Deciding on the topic
23/04/2025
During the study period, Nethaya and I explored different potential experiments that could be
done for our investigation. Initially, we wanted to do something regarding blood types, however
due to potential risks involved with blood we could not do so.
We then thought about doing an experiment involving enzyme activity. Earlier on in the year we
explored how temperature and pH effects enzyme amylase activity, but we did not explore how
substrate(starch) concentration or enzyme (amylase) concentration affected the rate of the
reaction. Therefore, for our investigation we planned to do an investigation exploring either
enzyme concentration or substrate concentration on reaction rate. Before we continue further,
we wanted to ask Dr. Bergen for his input on our experiment.
After discussing with Dr. Bergen, we found that an experiment using agar balls would be much
better for investigating how substrate concentration or enzyme concentration would affect the
rate of the reaction. Dr. Bergen provided us with another experiment testing enzyme activity
using pineapple juice and jelly as well as our initial experiment that we did earlier on in the year
for our SAC.
Experiments provided by Dr. Bergen:
Agar balls:
file:///C:/Users/TLE1281/AppData/Local/Microsoft/Windows/INetCache/Content.Outlook/UXG
XPA8A/A%20Twist%20On%20Measuring%20Catalase%20(3).pdf
Jelly (enzymes):
file:///C:/Users/TLE1281/AppData/Local/Microsoft/Windows/INetCache/Content.Outlook/UXG
XPA8A/Enzymes%20(Jelly-fruit).pdf
Enzyme (temperature and pH):
file:///C:/Users/TLE1281/AppData/Local/Microsoft/Windows/INetCache/Content.Outlook/UXG
XPA8A/Enzymes%20Temp-pH%20(STUDENT).pdf
29/04/2025
After discussing the options left for our investigation with Dr. Bergen, we decided to carry
through using the jelly experiment with varying enzyme concentration. We thought about how
we could take the simple jelly experiment and twist it to make it our own. Some of the things
that we discussed were to increase the complexity of the experiment is:
- Rather than using multiple different fruit juices (enzyme), instead we would use one and
have varying concentrations of that fruit juice.
- How do we more objectively measure the end point of the experiment (if the jelly sets or
not)?
This left us with several questions we needed to sort out for our experiment such as:
3|P age
INVESTIGATION
Yr 12 Biology Unit 3 and 4 (2025)
Thien-An Le
,Table of Contents
Contents
Table of Contents................................................................................................................... 1
Introduction and Preface ........................................................................................................ 2
Deciding on the topic ............................................................................................................. 3
Background Research ............................................................................................................ 5
Experiment Design ................................................................................................................. 8
Research Topic .................................................................................................................... 18
Experiment .......................................................................................................................... 20
Results and Observations: ................................................................................................... 22
Discussion .......................................................................................................................... 28
Summary/Analysis of Results............................................................................................ 28
Potential Extraneous Variables and Limitations in Method ................................................. 29
Further Research .............................................................................................................. 30
Conclusion .......................................................................................................................... 32
Acknowledgements ............................................................................................................. 33
1|P age
,Introduction and Preface
23/04/2025
The purpose of this logbook is to provide a basis for further learning in future studies. This
logbook will include my planning, thinking process, observations, data, research, and
conclusions.
The goal of my experiment is to formulate a scientific investigation that relates to the content
covered in VCE Biology Units 3 & 4. My partner (Nethaya) and I will conduct the experiment at
our school, Christway College, and the formation of my research and results will be done both
at school and at home.
This experiment aims to investigate the viscosity of jelly and how different concentrations of
enzyme will affect the viscosity of the jelly. Viscosity is a measure of a fluid’s resistance to
flow1. A fluid with a high viscosity will resist motion, while a fluid with a low viscosity will flow
more easily with little friction when in motion. When the jelly is set, the viscosity of the jelly is
said to be high, while when the jelly is not set, the viscosity of the jelly will be low. Enzymes are
organic molecules, typically proteins that catalyse (speed up) specific reactions.2 Enzyme
concentration refers to the amount of an enzyme that is present in a specific space. As the
enzyme concentration increases, the rate of the chemical reaction will increase as more
enzymes are able to bind to substrates and carry out the chemical reaction.
In the following experiment, the enzyme involved is bromelain, which is a digestive enzyme, that
is found in pineapple juice. For this investigation, the concentration of the pineapple juice and
the bromelain is said to be the same (for example 50% concentration pineapple juice=50%
bromelain enzyme). However, realistically, the concentration of the bromelain enzyme will
defer in the pineapple juice. One study found that in a 100% concentration pineapple juice, the
concentration of bromelain enzyme was said to be 0.43%3.
Furthermore, an important protein involved in this investigation
is gelatine. Gelatine is the substrate to the bromelain enzyme,
and when they bind together, the gelatine is digested by the
bromelain enzyme. Gelatine is a protein that is derived from
collagen and plays a significant role in jelly setting. In jelly, the
gelatine forms a complex matrix, which traps water between its
coils and nets, causing the jelly to become set and jiggly (figure
1).
When bromelain and gelatine is added together, the bromelain
digest the gelatine, thus there is insufficient gelatine available
for the jelly to set, therefore the viscosity of the jelly is low.
Figure 1 Coils and nets in gelatine
However, when bromelain and gelatine is not added together,
structure (matrix)
the bromelain does not digest the gelatine, and thus there is
enough gelatine available for the jelly to set, therefore the viscosity of the jelly is high.
1
https://www.princeton.edu/~gasdyn/Research/T-C_Research_Folder/Viscosity_def.html
2
Edrolo Textbook Ch.3
3
https://www.jstage.jst.go.jp/article/chikusan/88/3/88_335/_article/-
char/en#:~:text=Applying%20the%20load%20of%20gumminess,the%20pineapple%20juice%20was%20
0.43%25.
2|P age
, Deciding on the topic
23/04/2025
During the study period, Nethaya and I explored different potential experiments that could be
done for our investigation. Initially, we wanted to do something regarding blood types, however
due to potential risks involved with blood we could not do so.
We then thought about doing an experiment involving enzyme activity. Earlier on in the year we
explored how temperature and pH effects enzyme amylase activity, but we did not explore how
substrate(starch) concentration or enzyme (amylase) concentration affected the rate of the
reaction. Therefore, for our investigation we planned to do an investigation exploring either
enzyme concentration or substrate concentration on reaction rate. Before we continue further,
we wanted to ask Dr. Bergen for his input on our experiment.
After discussing with Dr. Bergen, we found that an experiment using agar balls would be much
better for investigating how substrate concentration or enzyme concentration would affect the
rate of the reaction. Dr. Bergen provided us with another experiment testing enzyme activity
using pineapple juice and jelly as well as our initial experiment that we did earlier on in the year
for our SAC.
Experiments provided by Dr. Bergen:
Agar balls:
file:///C:/Users/TLE1281/AppData/Local/Microsoft/Windows/INetCache/Content.Outlook/UXG
XPA8A/A%20Twist%20On%20Measuring%20Catalase%20(3).pdf
Jelly (enzymes):
file:///C:/Users/TLE1281/AppData/Local/Microsoft/Windows/INetCache/Content.Outlook/UXG
XPA8A/Enzymes%20(Jelly-fruit).pdf
Enzyme (temperature and pH):
file:///C:/Users/TLE1281/AppData/Local/Microsoft/Windows/INetCache/Content.Outlook/UXG
XPA8A/Enzymes%20Temp-pH%20(STUDENT).pdf
29/04/2025
After discussing the options left for our investigation with Dr. Bergen, we decided to carry
through using the jelly experiment with varying enzyme concentration. We thought about how
we could take the simple jelly experiment and twist it to make it our own. Some of the things
that we discussed were to increase the complexity of the experiment is:
- Rather than using multiple different fruit juices (enzyme), instead we would use one and
have varying concentrations of that fruit juice.
- How do we more objectively measure the end point of the experiment (if the jelly sets or
not)?
This left us with several questions we needed to sort out for our experiment such as:
3|P age
