Assignment 6A
Introduction:
The topic I have chosen to investigate for this assignment is Enzyme activity. The aim of this
assignment is to investigate how external factors affect enzyme activity. Factors I will be researching
include pH, temperature, concentration of the substrate, and the concentration of the enzymes
themselves using scientific evidence and prior experiments conducted to properly understand the
effect of these factors on enzymes. Investigating enzyme activity is crucial for scientific research as
enzymes are biological catalysts which control and speed up reactions in living organisms. The effect of
high temperature causes the enzyme activity to increase as the molecules gain more kinetic energy
and begin to collide more frequently, but when the temperature exceeds the optimum, the bonds that
support and hold the structure together break. This denatures the enzyme and its active site which
causes activity to decrease rapidly. Each individual enzyme has a specific optimum pH which allows
them to work the most effectively. However, if the pH increases of decreases below the optimum, the
bonds are altered in the enzyme which changes the shape of the active site. This prevents the enzyme
from binding to the substrate and leads to denaturation. As substrate concentration increases, the
enzyme activity also generally increases as more substrate molecules are available to collide with the
active sites. All the active sites become saturated therefore adding more substrate has very little effect
on the rate of reaction and allows it to reach its maximum rate. When enzyme concentration is
increased, the rate of reaction also increases as more active sites are available to bind to, but this only
continues to increase if there is enough substrate available. Limited substrate means more enzymes
will have no effect on the reaction rate and wont significantly increase it.
Main –
Factors Affecting Enzyme Activity:
Substrate Concentration
In source 1, one factor that effects enzyme activity is the substrate concentration. Substrate
concentration is the amount of substrate that is available to an enzyme-catalysed reaction. If the
substrate concentration is increased, the enzyme-catalysed rate of reaction also increases but only
when the enzyme is not fully saturated as of yet. This happens due to the larger amount of substrate
molecules that are available to collide with the enzyme’s active sites which increases how likely it is for
the successful formation of an enzyme-substrate complex. Although, the increase in substrate does not
continue for a prolonged period of time as once most of the enzyme active sites are filled, the enzyme
itself has a higher saturation which causes the reaction to work at its maximum rate. Therefore, any
more increases in substrate concentration little to no more additional increases within the reaction.
(Lowrie and Smith, 2019)
Source 2 similarly discusses the relationship between substrate concentration and the rate of enzyme-
substrate complex reactions is further supported by (Winterbottom, 2016) They explain how an
increase in substrate concentration increases the enzymes activity in the beginning due to the
opportunities there are for the substrate molecules to bind to the available enzyme active site. When
the substrate concentration continually increases, there is an increase in active sites that are occupied
until the enzyme itself becomes fully saturated. Both textbooks agree on the effects of substrate
concentration on enzyme activity confirms the relationship between the two.
Source 3 also takes into account how substrate concentration effects the reaction rate of enzymes. It
describes how any changes in the substrate concentration are able to change the rate of enzyme-
controlled reactions. (ScribdTranslations, 2026)
Source 1 is very useful due to it being an A-level biology textbook. It is designed specifically for
students that study biology as well as provides them with reliable scientific information in regard to
enzyme activity. (Lowrie and Smith, 2019) Source 2 is also extremely useful as it is also a biology
textbook which presents similar information about enzyme activity. Both textbooks stating very similar
facts of the relationship between substrate concentration and enzyme activity, therefore the accuracy
of the information is confirmed by multiple sources rather than just one. (Winterbottom, 2016)
Nonetheless, the textbooks mainly have summaries which are established by scientific knowledge but
don’t present any new or updated experimental results. Hence why peer-reviewed experimental studies
would be much more informational and would provide much stronger evidence of the investigations
included detailed data. Source 3 (ScridbTranslations, 2026) isn’t as reliable as the other sources due to
it being an uploaded document on a website where documents are shared. This means the quality and
scientific review of the material it provides is not as certain. Because of this, Source 3 can be used as
supporting information but not as the main evidence.
, Enzyme Concentration
Source 1 states that enzyme concentration generally increases the rate of reaction when the substrate
concentration is sufficient enough due to more enzyme molecules giving more active sites for the
substrate molecules to bind themselves to. As a result, there is an increase of formation of enzyme-
substrate complexes which increases the overall reaction rate of the enzyme. (Lowrie and Smith, 2019)
Source 4 investigates the relationship between the enzyme concentration and the enzyme activity. The
research conducted by them demonstrates how changes in enzyme concentration influences the
activity of enzymes in a biological system and provides scientific evidence which supports the
relationship between the enzyme concentration and enzyme activity. (Aragón and Sols, 1991) The
information stated in Source 4 is also consistent with that of Source 1. (Lowrie and Smith, 2019)
Effects of enzyme concentration are highly dependent on the substrate concentration that is available.
When there is a large amount of substrate, if the enzyme concentration is increased more active sites
can be provided and increases the rate of reaction. But if the substrate is limited, adding more
enzymes will have less of an effect at some point due to the insufficient amount of substrate molecules
for the additional active sites. (Aragón and Sols, 1991) (Lowrie and Smith, 2019)
Source 4 is a valuable source due to its scientific nature as well as it being a journal article which was
published by the FASEB Journal. The journal provides much stronger academic evidence in comparison
to a general educational website as all the scientific research that is published is peer-reviewed. It also
has direct relevance to enzyme concentration. Due to this, it can be used to support theoretical basis of
investigations. However, it does focus on regulation of enzyme activity within cells which is why it
doesn’t fully represent what happens in a school laboratory experiment when using particular enzymes
and substrates. Therefore, source 4 is very useful when used to explain scientific principles but would
need to be combined with another source to completely cover how an appropriate practical
investigation would be done for enzymes and substrates.
Both source 4 (Aragón and Sols, 1991) and source 1 (Lowrie and Smith, 2019) strengthened the
reliability of the fact that enzyme concentration effect’s reaction rate but it can also depend on other
controlled variables like substrate concentration, pH, and temperature.
Temperature
In source 1, it states as temperature increases, the enzyme and substrate molecules gain kinetic
energy and move much more rapidly which increases the frequency of the collisions that occur
between then enzymes and substrates. This increases the rate of enzyme-catalysed reactions.
Therefore, enzyme activity increases as it reaches its optimum temperature. When the temperature
rises above the optimum, the enzyme loses its specific shape of the active site due to the bonds which
hold the structure is disrupted. This is called denaturation and results in the decrease of enzyme
activity. (Lowrie and Smith, 2019)
In source 2 (Winterbottom, 2016), it explains how enzyme activity is increased as temperature
increases until it reaches its optimum then the activity decreases because of the enzyme becoming
denatured. Source 5 also names temperature as a main factor that has an effect on enzyme activity as
well as describes the relationship between an increase in temperature, optimum temperature, and
denaturation of enzymes. (A Level Biology, 2016)
All 3 sources provide information on how temperature effects enzyme and confirms with confidence
that the general relationship between the two is accurate. Source 1 (Lowrie and Smith, 2019) and
source 2 (Winterbottom, 2015) are both established educational textbooks however source 5 (A Level
Biology, 2016) is an educational website on biology. The textbooks are much more reliable when doing
academic work as they’ve been produced specifically for formal academic resources. But it is still very
useful for reinforcing the general scientific explanation of the relationship between temperature and
enzyme activity. They are also useful when needing to plan an investigation as the temperature would
be able to be controlled when the investigation is designed to investigate either substrate or enzyme
concentration. In the event that temperature is altered in between experiments, the enzyme activity
could be affected.
pH
Source 1 details that enzymes need particular conditions in order for their active sites to keep their
correct shape, size and chemical properties. Depending on the enzyme, different pH levels are needed
Introduction:
The topic I have chosen to investigate for this assignment is Enzyme activity. The aim of this
assignment is to investigate how external factors affect enzyme activity. Factors I will be researching
include pH, temperature, concentration of the substrate, and the concentration of the enzymes
themselves using scientific evidence and prior experiments conducted to properly understand the
effect of these factors on enzymes. Investigating enzyme activity is crucial for scientific research as
enzymes are biological catalysts which control and speed up reactions in living organisms. The effect of
high temperature causes the enzyme activity to increase as the molecules gain more kinetic energy
and begin to collide more frequently, but when the temperature exceeds the optimum, the bonds that
support and hold the structure together break. This denatures the enzyme and its active site which
causes activity to decrease rapidly. Each individual enzyme has a specific optimum pH which allows
them to work the most effectively. However, if the pH increases of decreases below the optimum, the
bonds are altered in the enzyme which changes the shape of the active site. This prevents the enzyme
from binding to the substrate and leads to denaturation. As substrate concentration increases, the
enzyme activity also generally increases as more substrate molecules are available to collide with the
active sites. All the active sites become saturated therefore adding more substrate has very little effect
on the rate of reaction and allows it to reach its maximum rate. When enzyme concentration is
increased, the rate of reaction also increases as more active sites are available to bind to, but this only
continues to increase if there is enough substrate available. Limited substrate means more enzymes
will have no effect on the reaction rate and wont significantly increase it.
Main –
Factors Affecting Enzyme Activity:
Substrate Concentration
In source 1, one factor that effects enzyme activity is the substrate concentration. Substrate
concentration is the amount of substrate that is available to an enzyme-catalysed reaction. If the
substrate concentration is increased, the enzyme-catalysed rate of reaction also increases but only
when the enzyme is not fully saturated as of yet. This happens due to the larger amount of substrate
molecules that are available to collide with the enzyme’s active sites which increases how likely it is for
the successful formation of an enzyme-substrate complex. Although, the increase in substrate does not
continue for a prolonged period of time as once most of the enzyme active sites are filled, the enzyme
itself has a higher saturation which causes the reaction to work at its maximum rate. Therefore, any
more increases in substrate concentration little to no more additional increases within the reaction.
(Lowrie and Smith, 2019)
Source 2 similarly discusses the relationship between substrate concentration and the rate of enzyme-
substrate complex reactions is further supported by (Winterbottom, 2016) They explain how an
increase in substrate concentration increases the enzymes activity in the beginning due to the
opportunities there are for the substrate molecules to bind to the available enzyme active site. When
the substrate concentration continually increases, there is an increase in active sites that are occupied
until the enzyme itself becomes fully saturated. Both textbooks agree on the effects of substrate
concentration on enzyme activity confirms the relationship between the two.
Source 3 also takes into account how substrate concentration effects the reaction rate of enzymes. It
describes how any changes in the substrate concentration are able to change the rate of enzyme-
controlled reactions. (ScribdTranslations, 2026)
Source 1 is very useful due to it being an A-level biology textbook. It is designed specifically for
students that study biology as well as provides them with reliable scientific information in regard to
enzyme activity. (Lowrie and Smith, 2019) Source 2 is also extremely useful as it is also a biology
textbook which presents similar information about enzyme activity. Both textbooks stating very similar
facts of the relationship between substrate concentration and enzyme activity, therefore the accuracy
of the information is confirmed by multiple sources rather than just one. (Winterbottom, 2016)
Nonetheless, the textbooks mainly have summaries which are established by scientific knowledge but
don’t present any new or updated experimental results. Hence why peer-reviewed experimental studies
would be much more informational and would provide much stronger evidence of the investigations
included detailed data. Source 3 (ScridbTranslations, 2026) isn’t as reliable as the other sources due to
it being an uploaded document on a website where documents are shared. This means the quality and
scientific review of the material it provides is not as certain. Because of this, Source 3 can be used as
supporting information but not as the main evidence.
, Enzyme Concentration
Source 1 states that enzyme concentration generally increases the rate of reaction when the substrate
concentration is sufficient enough due to more enzyme molecules giving more active sites for the
substrate molecules to bind themselves to. As a result, there is an increase of formation of enzyme-
substrate complexes which increases the overall reaction rate of the enzyme. (Lowrie and Smith, 2019)
Source 4 investigates the relationship between the enzyme concentration and the enzyme activity. The
research conducted by them demonstrates how changes in enzyme concentration influences the
activity of enzymes in a biological system and provides scientific evidence which supports the
relationship between the enzyme concentration and enzyme activity. (Aragón and Sols, 1991) The
information stated in Source 4 is also consistent with that of Source 1. (Lowrie and Smith, 2019)
Effects of enzyme concentration are highly dependent on the substrate concentration that is available.
When there is a large amount of substrate, if the enzyme concentration is increased more active sites
can be provided and increases the rate of reaction. But if the substrate is limited, adding more
enzymes will have less of an effect at some point due to the insufficient amount of substrate molecules
for the additional active sites. (Aragón and Sols, 1991) (Lowrie and Smith, 2019)
Source 4 is a valuable source due to its scientific nature as well as it being a journal article which was
published by the FASEB Journal. The journal provides much stronger academic evidence in comparison
to a general educational website as all the scientific research that is published is peer-reviewed. It also
has direct relevance to enzyme concentration. Due to this, it can be used to support theoretical basis of
investigations. However, it does focus on regulation of enzyme activity within cells which is why it
doesn’t fully represent what happens in a school laboratory experiment when using particular enzymes
and substrates. Therefore, source 4 is very useful when used to explain scientific principles but would
need to be combined with another source to completely cover how an appropriate practical
investigation would be done for enzymes and substrates.
Both source 4 (Aragón and Sols, 1991) and source 1 (Lowrie and Smith, 2019) strengthened the
reliability of the fact that enzyme concentration effect’s reaction rate but it can also depend on other
controlled variables like substrate concentration, pH, and temperature.
Temperature
In source 1, it states as temperature increases, the enzyme and substrate molecules gain kinetic
energy and move much more rapidly which increases the frequency of the collisions that occur
between then enzymes and substrates. This increases the rate of enzyme-catalysed reactions.
Therefore, enzyme activity increases as it reaches its optimum temperature. When the temperature
rises above the optimum, the enzyme loses its specific shape of the active site due to the bonds which
hold the structure is disrupted. This is called denaturation and results in the decrease of enzyme
activity. (Lowrie and Smith, 2019)
In source 2 (Winterbottom, 2016), it explains how enzyme activity is increased as temperature
increases until it reaches its optimum then the activity decreases because of the enzyme becoming
denatured. Source 5 also names temperature as a main factor that has an effect on enzyme activity as
well as describes the relationship between an increase in temperature, optimum temperature, and
denaturation of enzymes. (A Level Biology, 2016)
All 3 sources provide information on how temperature effects enzyme and confirms with confidence
that the general relationship between the two is accurate. Source 1 (Lowrie and Smith, 2019) and
source 2 (Winterbottom, 2015) are both established educational textbooks however source 5 (A Level
Biology, 2016) is an educational website on biology. The textbooks are much more reliable when doing
academic work as they’ve been produced specifically for formal academic resources. But it is still very
useful for reinforcing the general scientific explanation of the relationship between temperature and
enzyme activity. They are also useful when needing to plan an investigation as the temperature would
be able to be controlled when the investigation is designed to investigate either substrate or enzyme
concentration. In the event that temperature is altered in between experiments, the enzyme activity
could be affected.
pH
Source 1 details that enzymes need particular conditions in order for their active sites to keep their
correct shape, size and chemical properties. Depending on the enzyme, different pH levels are needed
