The effect of different water temperature on enzyme activity in laundry detergent/ effectiveness of enzyme activity depending on water temp- DRAFT

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Part A - Deconstruct 2,352

-863599223520What effect does temperature of water have on enzyme activity in laundry powder?

-8635992235201447800223520Enzymes in laundry powder

14478002235203759200223520How can the effectiveness of enzymes be measured?

3759200223520-876299871220An enzyme is a globular protein that speeds up or catalyses a specific chemical reaction in cells. Catalysing means that it speeds up the rate of reaction without making any further changes. Enzymes are used in many aspects of daily life, such as using laundry powder to improve stain removal on clothes. However, in order for the laundry powder to work properly, it is mixed with water. Some enzymes react different depending on the temperature of the water. For instance, some laundry powders may contain stronger enzymes which aid in the removal of stains more efficiently. The temperatures of water which enzymes commonly work best in are luke warm and hot, not boiling. This is due to the powder and enzymes dissolving better in the warm to hot waters, which activate the enzymes, resulting in enhanced stain removal. In boiling water the enzymes denature, which decreases the rate of reaction. Why test the temperature? Testing the effect of different water temperatures on enzyme productivity, is the most adequate analysis and it is likely to develop clear results/solutions.

-8762998712202603500896620In terms of this experiment, the enzyme activity in the laundry powder can be measured using a couple of factors. In the context of stain removal, the effectiveness of the enzyme on stain removal can be measured by:

Measuring the effectiveness of the enzyme (protease) by how much stain is removed from the cloth, meaning, the whiter the cloth is, the better due to more stain having been removed by the enzyme in the laundry powder.

All the other variables will remain constant throughout the experiment to maintain an even flow in results at the end of the investigation

The aspects which will remain constant are the amount of enzyme which is used, the amount of water in the beaker, the amount of stain (beetroot juice or the size of stain on the cloth), the cloth size, and the time to soak the stained cloth in different temperature water with laundry powder.

2603500896620

-876299210820Main enzymes used in laundry powders & how they work

Enzymes are categorised based on the reactions that they help catalyse; each enzyme is specific and complementary to one substrate, which is why there are many types of enzymes. The enzymes which are commonly present and used in laundry powders consist of:

Lipases, which assist in the breakdown of fats & oils

Proteases (proteases were the first enzyme to be used in the process of stain removal, and is the most commonly used enzyme in laundry powders). Proteases break down protein chains on materials (for instance, stains from blood and sweat, which are made up of protein molecules). Proteases are found in the body, though, for the purpose of using them for laundry powders, they are attained by genetically modifying bacteria.

In most laundry powders, both lipase and protease enzymes are found; as they work together to remove oil and larger protein stains. These compounds make them perfectly ideal for removing stains from soiled clothes

Other enzymes which are used in laundry powders include:

Amylases

mannanases

cellulases

pectinases

-8762992108202641600210820Factors involved in selecting enzymes to use in laundry detergent

Should be stable at high pH and temp, should be able to remove protein and lipid stains

Then select one enzyme and develop a method to investigate one factor that might influence a manufacturers directions for using that enzyme in their laundry detergent.?????

2641600210820

-876299-144779 Tolerance limits of enzymes

In order for the enzymes in laundry detergent to work properly, several factors are taken into consideration:

Wash/water PH: At the optimum water pH level, the enzyme activity in the laundry powder is most effective. The best pH for washing clothes is 7- 10.5. This is because more neutral- basic conditions are needed to wash clothes so that the water does not breakdown/damage clothes by being too acidic. Temperature: At temperatures that are too high, enzymes can become denatured, meaning the rate of reaction would decrease as enzymes are not able to catalyse reaction. This is why, in terms of washing clothes, warm- hot temperature water is used so it is just the right environment for enzymes to activate. Enzymes in laundry powders function best at temperatures of 20- 60 degrees.

Configuration of detergent: This refers to the chemical makeup of the laundry powder or what else is present in it (other ingredients/surfactants/bleaching species). They could either enhance the enzymes stain removal or denature it by interference.

Type of stain being removed: the enzymes in laundry powders are most effective at removing stains if the substrate (stains) are simpler to breakdown. However, this may not always be the case, as the protein and oil configuration of some stains can be varied and difficult to remove. This is why enzyme specificity is important.

Enzymes present specificity for the reactions they catalyse, and hence for each enzyme, only physically comparable compounds acts as substrates (or reactants). Specificity is a constructive aspect for the upkeep of fabrics as the enzyme can be selected with a great likelihood of not spoiling any fabrics; nonetheless specificity also leads to the requirement of having various enzymes.

Water hardness (mineral content): other minerals (calcium and magnesium carbonates) which could potentially be present in the water could alter the effectiveness of stain removal. This is mainly due to the other minerals interfering with the enzymes needed for stain removal, therefore, the enzymes would not work to their full potential.

Presence of inhibitors: Slows down/ prevents reaction which reduces activity of enzyme, leading to the proteins and oils not being completely broken down, therefore, the stain not being thoroughly removed.

-876299-144779

-863599274320 Chosen enzyme

Protease: Temp of water, proteases do not need hot water for them to be activated/remove stains, most effective and efficient at optimum temperature for protease, 40 degrees, maximum temperature where they still effective at was 50 degrees, protease: (scientific names, peptidase or proteinase) is an enzyme that catalyses (increases reaction rate or speeds up), breaks down proteins (stains) into smaller polypeptides or single amino acids, and encourages the formation of new protein products. Most common and easy to obtain.

Limitations: there snot just protease in laundry detergent, also consists of other stuff, each scoop would have different enzyme concentration/content

-863599274320

Part B - Design

For experiment: use different water temperatures ranging from 20- 60 degrees (thermometer), if too hot: denatures enzyme, too cold: decreases in enzyme activity,

Use beetroot juice stain on white cloths

Set times

The cloth with the weakest colour on it would be considered the most effective test

Intro/ background info (hypothesis/ aim is stated at the end of the intro)

Variable table (how and why)

Independent Dependant Controlled variables

Temperature of water Protease enzyme reaction (depends on water temperature) Time of soaking

Effectiveness of stain removal Method used

Cloth size

Amount of laundry powder

Amount of water

Risk assessment

Materials

Vanish Oxi-Action laundry powder (specifically says it contains protease)

Water

Thermometer

3 medium sized bowls or beaker

3 7x7 white cloths

Scissors

Ruler

3 tbsp beetroot juice

Pipette

Stirrer (either spoon or stick?)

Timer

Camera (phone)

Method (water to laundry powder ratio??) also write why I did each step

Using a thermometer, fill 3 bowls (or beaker) with 1 and a cups (375 mls) of lukewarm (36.5C), hot (60C) and boiling (100C) water (if beaker, use less water, use 500ml or 250ml beaker)

Add scoop of laundry powder (Vanish Oxi- Action) into each bowl/beaker, mix a bit to dilute/ distribute it evenly throughout the water to get even results

Cut 3 pieces of 7x7 cm (49cm) white cloth

Stain each cloth with 1 tbsp of beetroot juice using a pipette

Place a cloth in each bowl/beaker and let them soak for 1 hour (take photos of current stains to compare to later results)

Remove the cloths and observe the differences in stain removal between the lukewarm, hot and boiling water (take photos for reference)

6477007620064770076200

1219200457207x7 cm (cloth size)

121920045720

References

https://www.persil.com/uk/laundry/laundry-tips/washing-tips/enzymes-in-biological-detergents-the-facts-about-laundry-detergents-and-how-they-work.html

https://www.sciencedirect.com/topics/social-sciences/enzymes

C Grade example file:///C:/Users/asraa/Downloads/Deconstruct_1_response_annotated.pdf

http://steamexperiments.com/experiment/cleaning-time-using-the-power-of-enzymes/

Image: Retseck.G, https://www.scientificamerican.com/article/exploring-enzymes/# (do I include author of website?)

https://www.sciencedirect.com/topics/social-sciences/enzymes#:~:text=The%20performance%20of%20enzymes%20in,be%20removed%20and%20water%20hardness.

1167005

Describe image

Class notes

2 pages (max) for each deconstruct and design

Colour coding

Add how washing machines work (rapid movement, agitation, collision with substrate)

Part C - Catalase enzyme practical report- DRAFT

Introduction

Enzymes are biological catalysts that function in the cell to lower the activation energy of a reaction, allowing it to proceed more quickly. Each enzyme has a distinct three-dimensional structure (specificity) that complements the form of its specific substrate, allowing two molecules to bind more easily. As the catalase's active site is tailored to the structure of hydrogen peroxide (substrate), hydrogen peroxide is broken down into oxygen and water when the two encounter. Hydrogen peroxide is a toxic byproduct formed during cellular metabolism, which can have harmful consequences on the body when it builds up. The enzyme catalase is utilised by the cell to break it down as it is produced. The rate of reaction is affected by the substrate concentration. If the amount of substrate molecules present is fewer than the amount of enzymes present, the reaction will proceed swiftly, though, the amount of products synthesized will be limited. When the number of substrate molecules exceeds the amount of enzymes present, the number of enzyme-substrate complexes generated at any given time is limited, restricting the pace of reaction. This is due to hHydrogen peroxide isbeing a byproduct formed duringby biochemical reactions interactions involving in cellular metabolism and immune cells, it is related to biological reactions; which yet, a build-up of this substance can have harmful consequences on the body when it builds up. The enzyme catalase is utilised by the cell to break it down as it is produced. As a result, the amount of hydrogen peroxide present affects how long it takes catalase to break it down. This investigation willAs a result of determinedetermining how concentration influences catalase enzyme activity, to establishit will be clear at whichat concentration of catalase works best in living cells before the rate of reaction plateaus and continues at a constant rate.

Aim

The goal of this experiment iswas to observe how varying substrate concentrations altered the rate of reaction among enzymes and substrates. Catalase is knownwas found to break down hydrogen peroxide (H2O2) into water (H2O) and oxygen (O2), resulting in the production of foam as the gas is formed during laboratory conditions. The pace of reaction could then be determined by measuring the amount of foam produced in a given timeframe.

To find the effect of substrate concentration on enzyme activity.

Hypothesis

Between 0% substrate concentrations to 6% substrate concentration, the rate of reaction will rise significantly until remaining stable at 6%. This is due to catalase being a prevalent enzyme component of cell membranes, therefore, it would be abundant; nevertheless, after 6 percent, I believe the quantity of substrate will be rare in cells, implying that all catalase active sites are constantly being used in the effort to break down the hydrogen peroxide. As a result, the reaction speed is reduced to a specified rate.

If the concentration of H202 is increased, then the foam produced will also increase

If the concentration of H202 added to catalyse is increased, then the volume of O2 will also increase

Materials

18mL catalase extract (spinach, pureed & filtered)

10mL cold hydrogen peroxide (H202) solution of each of the following concentrations (0, 1, 2, 3, 4, 5, 6%)

1 x 5mL syringe

7 x 50mL measuring cylinder

7 x 10mL measuring cylinder

1 x stopwatch

Variables

Independent

Concentration of hydrogen peroxide (H2O2) substrate. This will be altered by using varied hydrogen peroxide beakers, each with a different concentration. By using main solutions of various concentrations ensures that they are all accurate and that their concentrations are recognised.

Dependent

Rate of reaction. The findings will be determined by calculating the volume of foam produced during a 30-second timeframe and comparing them to get the optimal enzyme activity concentration.

Controlled

Measuring the rate of reaction after 30 seconds. This is critical for achieving correct results, since, if the foam volume is inaccurately measured, the rate of reaction will be incorrect as well.

Equal volumes of catalase and H2O2 in each measuring cylinder. This guarantees that relative concentrations are consistent, which is essential for obtaining valid results. This is because the rate of reaction would have been affected if one beaker contained more enzymes or a larger amount of substrates.

Temperature. Enabling all catalase extracts and hydrogen peroxide concentrations to be in room temperature will keep them under control. If this isn't regulated, the temperature differential will impact the rate of reaction, resulting in erroneous results.

Uncontrolled

Risk/safety assessment

Although the dangers in this experiment were small, attention was required when handling the H2O2 (hydrogen peroxide) because it can be highly corrosive and irritate the skin. Dilute solutions of Hydrogen Peroxide were prepared beforehand by a staff member at the school. Safety glasses, gloves and lab coats were worn, and necessary action, such as rinsing, was taken if any made contact with skin. Glassware (such as beakers) were also positioned in the centre of workstations to ensure that no spillage occurred. Overall this practical experiment was considered to be low risk. Low Risk __X__________________________________High Risk

CHEMICAL/APPARATUS

HAZARD

PRECAUTIONS HAZARD RESPONSE

Hydrogen Peroxide (H2O2)

Glassware (beakers, measuring cylinders,

Procedure/method

1. Using a 10mL measuring cylinder, measure 6mL of the 0% H202 and pour it into a 50mL measuring cylinder.

2. Measure 3mL of the catalase extract with the syringe.

3. Add the 3mL of catalase extract to the H202 in the 50mL measuring cylinder and immediately start timing.

4. After 30 seconds record the level of foam (mL) in the measuring cylinder and record your data in a table.

5. Calculate the volume of foam produced by the following formula: final volume 9 mL and record your data in a table.

6. Repeat steps 1 5 for the other concentrations of H202 (1, 2, 3, 4, 5, 6 %)

7. Calculate the rate of reaction using the following formula:

Rate of catalase activity (mL/second) = Volume of foam produced (mL)

seconds

8 .Collate class data to provide replicates and average.

Results ON GMAIL

Rate of Catalase Activity (ml/s)

Concentration of Hydrogen Peroxide (H2O2) (%) Group 1 Group 2 Group 3 Group 4 Group 5 Average

0 0 0 0.07 0 0 0.07

1 0.1 0.13 0.88 0.08 0.25 0.26

2 0.1 0.17 0.1 0.12 0.75 0.13

3 0.08 0.22 0.12 0.14 0.8 0.15

4 0.13 0.22 0.15 0.17 0.11 0.17

5 0.13 0.25 0.15 0.2 0.1 0.18

6 0.12 0.25 0.13 0.15 0.12 0.16

Discussion

Analysis

According to the findings, the concentration at which hydrogen peroxide (H2O2) is broken down the fastest into H2O and O2 is 6%. The reaction rate was 21ml/s at this concentration. The slowest rate of reaction occurred at 0%, since it was N/A ml/s. As a result, this evidence confirms the idea that a concentration of 6% would be too high for the amount of catalase enzymes present in the 5ml of extract, causing the rate to plateau. This was clear as, although the rate of reaction did plateau at 4%-6%, it stayed constant at that level. The data does shows a trend of a continuous increase in reaction rate as the substrate concentration rises. This is depicted on the graph by a -dosage response curve line that includes both groupbothgroup individual and average data from the class. This was anticipated since the rate of reaction is equivalent to the amount of substrate in the solution, with some constraints on how quickly it may go. This is due to catalase, being an enzyme, there are only so many active sites accessible at any given time for substrates to bind to and a reaction to take place. As a result, if all of them are used up, the remaining substrate in the solution is unable to attach to an enzyme and must await for catalase to break down other substrates prior to binding to the next. As a result, the rate of reaction remains constant, though, it can no longer rise.

Evaluation

Random/systematic errors

In this experiment, there were various possible instances of random error, such as not measuring the foam accurately after 30 seconds. This is because the foam may have risen at an angle or the measurement was not taken at eye level, resulting in an inaccurate result. Due to this, it may have had a minor yet significant impact on the data, since the preliminary measurements may have been inaccurate, which would have caused the rate of reaction recording to be incorrect, which then could have changed the graph's appearance. A further source of random error could be some of the hydrogen peroxide getting trapped on the edge of the beaker as it was being poured in. This may have resulted in the result being tainted as not all of the measured volume interacted with the catalase. This would have been influenced by a variance in how dependable the provided rate of reaction was since the amount of hydrogen peroxide combined with the catalase is unknown. Another form of random error could be that the amounts required for each component were measured erroneously. This would have had an impact on the data since the controlled variables were not effectively managed, resulting in incorrect values for the rate of reaction; as a result, the data is not dependable and does not provide accurate numbers. While every precaution was undertaken to avoid random errors to a feasible extent, it is still conceivable that a few of them occurred. As a result, the data has a minor amount of scepticism, and the trial would need to be repeated to see if the data coincides with and confirms the primary data. The content of catalase extract will be a source of ambiguity. Was the concentration entirely evened out by the mixing of the catalase, or were certain extracts greater concentrated over others? The findings would have been impacted since there would have been an increased amount of enzymes available to break down the hydrogen peroxide faster if a few extracts were more concentrated, thereby accelerating the reaction rate. Additionally, a systematic error could have occurred as the measuring cylinders were inaccurate, resulting in amounts of extract and H2O2 being measured inaccurately on a regular basis. This is due to the fact that the measuring cylinders are indeed of school laboratory standard, thus, the result would also have been influenced by the volumes of catalase and hydrogen peroxide being greater or lesser than indicated. As a result, the claimed quantities in the gathered data and the correct values of the experiment may have been in conflict.

The data is reliable to a good extent because the procedure was followed accurately and correctly individually, as well as repeating each group repeating the experiment to get an average value for each concentration. However, the experiment has elements of unreliability because

The data accuracy is average; however, the 6 percent concentrations had a low accuracy, with values varying by up to 0.3 ml/s from group to group, which is relevant when the overall values are between 0 and 1. The other concentrations, on the other hand, were more accurate since they changed to a lesser extent, culminating in a more reliable number for on the graph. Since the accepted values are unclear, the data's reliability is low, and factors of random and systematic errorall contribute to the data's inaccuracy. Despite a few components of authenticity, such as the catalase enzyme breaking down the hydrogen peroxide component, the experiment is generally inaccurate since the concentrations do not accurately representthe condition in the cell. As the cell is constantly breaking down the hydrogen peroxide which is created as a result of other cellular activities, there will almost never be a moment when the cell is at a continuous optimal concentration. This leads to the following point: the experiment is notconducted in cellular circumstances, which limits its trustworthiness. It's unknown whether the experiment would have yielded opposite findings if it had been conducted in cellular activity. Despite the fact that the experiment was largely flawed, unpredictable, vague, and erroneous, the procedure succeeded to a substantial extent. This is due to the fact that the objective was to observehow changing substrate concentrations affected reaction rate, and it was accomplished. Measuring the foam was a fantastic approach to estimate the rate of reaction because oxygen is a result of the reaction. However, one enhancement that should be addressed is that the concentrations should be prepared as soon as feasibleprior tothe experiment. As a result, the solution does not have time to integrate, and the concentration value ismore precise to the documented value.

Conclusion

Ultimately, the experiment's goal was accomplished as it was discovered how varying substrate concentrations impacted reaction rates. Since there was no substrate for the enzyme to operate with at 0% concentration, this resulted in no rate of reaction (N/A ml/s). Nevertheless, at 6% concentration, the rate of reaction had attained its ideal at 21ml/s, showing anything over these concentration levels will not increase the frequency of reaction as there are only a specific amount of enzymes in a 5ml pureed spinach extract. This emphasises the pattern that the rate of reaction rose as substrate concentration increased, until the rate plateaued at 6% and above, indicating that it had achieved its maximum. The experiment's limitations consist of the fact that the concentration range is fairly narrow, and a few higher numbers potentially could have been fascinating to see. Nonetheless, the results met the experiment's objectives.

Stage 2 Biology

Assessment Type 1: Investigations Folio

Deconstruction and Design Investigation: Factors Affecting Enzyme Activity in Laundry Detergents

Enzymes are often added to laundry detergents to help remove stains by breaking down the macromolecules that cause them. There are different kinds of enzymes which may be used depending on the type of macromolecule. When manufacturers are considering which enzyme(s) to add, they need to take into account cost, safety, and the various conditions under which they may be used.

Many factors affect the effectiveness of enzymes during the washing of clothes etc. These questions include: Which enzymes may assist in the washing process? Why? What factors affect enzyme activity? How can the suitability of an enzyme for use in laundry detergent be tested?

You will consider and explore the question: How can a washing powder enzyme be used to remove stains most efficiently?

You will then design an experiment to determine the effect of one factor on the activity of one enzyme that may be used in a laundry detergent.

You will either use one of your own designs or use a predetermined method.

ADeconstruct the problem

Consider the question and could it be tested.

Research which enzymes can assist in the washing process and how they work. Consider the factors can affect their activity.

Explore the various factors that would be involved in selecting an enzyme to use in laundry detergent.

Make informed decisions about a process that could be used to determine experimentally how one factor might affect enzyme activity and how this could be measured in the context of stain removal.

Explore the risk factors involved in the process.

Then select one enzyme and develop a method to investigate one factor that might influence a manufacturers directions for using that enzyme in their laundry detergent.

BDesigning your own investigation

Use the guidelines on Page 7 of the subject outline to help you design your investigation. Also, keep in mind the requirements of the practical report that are described on page 53 of the subject outline.

Annotate your deconstruction and design to justify the decisions you have made about such things as the weed you have chosen, the independent and dependent variables, how and why you will control other variables, number of trials, measurements.

Evidence of deconstruction, the method/procedure chosen as most appropriate, and a justification of the plan of action must be a maximum of 4 sides of an A4 page.

Part A and B will be completed individually and will be submitted for assessment on:

__________________________

CImplementing an investigation

In defined groups, students in consultation with the teacher will select one method to implement and to collect data.

DWriting an individual report

You will use the data collected to write an individual report using the specification on Page 53 of the subject outline. This report is based on the investigation that was actually undertaken in Part C.

The report should be a maximum of 1500 words if written, or a maximum of 10 minutes for an oral presentation, or the equivalent in multimodal form.

Only the following sections of the report are included in the word count:

introduction

analysis of results

evaluation of method/procedure

conclusion.

The evidence of the deconstruction and design component must be attached to the practical report.

The practical report with the deconstruction and design summary and individual method attached is to be submitted on:

______________________________________

Performance Standards

Investigation, Analysis and Evaluation Knowledge and Application

A Critically deconstructs a problem and designs a logical, coherent, and detailed biological investigation.

Obtains, records, and represents data, using appropriate conventions and formats accurately and highly effectively.

Systematically analyses and interprets data and evidence to formulate logical conclusions with detailed justification.

Critically and logically evaluates procedures and their effect on data. Demonstrates deep and broad knowledge and understanding of a range of biological concepts.

Applies biological concepts highly effectively in new and familiar contexts.

Critically explores and understands in depth the interaction between science and society.

Communicates knowledge and understanding of biology coherently, with highly effective use of appropriate terms, conventions, and representations.

B Logically deconstructs a problem and designs a well-considered and clear biological investigation.

Obtains, records, and represents data, using appropriate conventions and formats mostly accurately and effectively.

Logically analyses and interprets data and evidence to formulate suitable conclusions with reasonable justification.

Logically evaluates procedures and their effect on data. Demonstrates some depth and breadth of knowledge and understanding of a range of biological concepts.

Applies biological concepts mostly effectively in new and familiar contexts.

Logically explores and understands in some depth the interaction between science and society.

Communicates knowledge and understanding of biology mostly coherently, with effective use of appropriate terms, conventions, and representations.

C Deconstructs a problem and designs a considered and generally clear biological investigation.

Obtains, records, and represents data, using generally appropriate conventions and formats with some errors but generally accurately and effectively.

Undertakes some analysis and interpretation of data and evidence to formulate generally appropriate conclusions with some justification.

Evaluates procedures and some of their effect on data. Demonstrates knowledge and understanding of a general range of biological concepts.

Applies biological concepts generally effectively in new or familiar contexts.

Explores and understands aspects of the interaction between science and society.

Communicates knowledge and understanding of biology generally effectively, using some appropriate terms, conventions, and representations.

D Prepares a basic deconstruction of a problem and an outline of a deconstruction and biological investigation.

Obtains, records, and represents data, using conventions and formats inconsistently, with occasional accuracy and effectiveness.

Describes data and undertakes some basic interpretation to formulate a basic conclusion.

Attempts to evaluate procedures or suggest an effect on data. Demonstrates some basic knowledge and partial understanding of biological concepts.

Applies some biological concepts in familiar contexts.

Partially explores and recognises aspects of the interaction between science and society.

Communicates basic biological information, using some appropriate terms, conventions, and/or representations.

E Attempts a simple deconstruction of a problem and a procedure for a biological investigation.

Attempts to record and represent some data, with limited accuracy or effectiveness.

Attempts to describe results and/or interpret data to formulate a basic conclusion.

Acknowledges that procedures affect data. Demonstrates limited recognition and awareness of biological concepts.

Attempts to apply biological concepts in familiar contexts.

Attempts to explore and identify an aspect of the interaction between science and society.

Attempts to communicate information about biology.

-876300-402167Photosynthesis is a process plants undertake to produce oxygen and energy and is the primary factor that can inhibit crop yield. Sunlight, water, and carbon dioxide are reactants in the process and thus, the availability of these products is vital in determining the rate of photosynthesis and hence, increasing crop yield.

Increasing the efficiency of photosynthesis can also occur from other factors, with recent studies focusing on:

O The pores of leaves to allow for increased exchange of carbon dioxide and water vapour.

O Enhancing activity of the main photosynthetic enzyme, Rubisco.

O Improving the capacity of leaves to transport electrons.

O Improving flow of carbon dioxide through internal layers of leaf.

However, Professor von Caemmerer, a researcher at The Australian National University (ANU) who is a co-author of a recent study examining the photosynthetic manipulations to plants that can increase crop yield states "We know that it is not as simple as saying that improving photosynthesis will increase yield. The answer depends on the situation. For example, when exposed to increased rates of photosynthesis, Sorghums yield can decrease in crops with low water availability. Models suggest this can be monitored with carbon dioxide entry and water vapour exit through plant pores (University of Queensland, 2019; Wu et al. 2019).

Additionally, photorespiration reduces the efficiency of photosynthesis. Photorespiration predominantly occurs in C3 plants (not C4 alike photosynthesis). This process wastes some of the already fixed carbon and energy of the cell, resulting in less efficient glucose production process. Rubisco is responsible for which process occurs (Lakna 2018).

Cyanobacteria and some land plants are able to concentrate carbon dioxide in close proximity to rubisco, thus preventing photorespiration. However, plants that do not possess these mechanisms must expend large amount of protein so that the rubisco is able to conduct carbon fixation, thus reducing yield and biomass production. Research is being investigated into replacing rubisco with faster enzymes with carbon-concentrating mechanisms (Hansen, n.d.).

From the plant species listed, specimens of water hyssop will be used as rubisco was not able to be monitored due to available resources, however, water hyssop is a C3 plant and thus enzymes with carbon-concentrating mechanisms could be used to prevent the loss of yield.

00Photosynthesis is a process plants undertake to produce oxygen and energy and is the primary factor that can inhibit crop yield. Sunlight, water, and carbon dioxide are reactants in the process and thus, the availability of these products is vital in determining the rate of photosynthesis and hence, increasing crop yield.

Increasing the efficiency of photosynthesis can also occur from other factors, with recent studies focusing on:

O The pores of leaves to allow for increased exchange of carbon dioxide and water vapour.

O Enhancing activity of the main photosynthetic enzyme, Rubisco.

O Improving the capacity of leaves to transport electrons.

O Improving flow of carbon dioxide through internal layers of leaf.

3472815-399415Photosynthesis is a chemical reaction and hence the rate of occurrence is used to measure its efficiency. The rate of photosynthesis can be measured using various procedures and devices, including input and output monitoring techniques as below:

Measuring the uptake of carbon dioxide, which indicates the rate of photosynthesis because carbon dioxide is a reactant in the process of photosynthesis and thus the amount of carbon dioxide taken in determines the rate at which the reaction is occurring (Trimble, 2019). Measuring this factor can be conducted by various methods, including measuring the pH (since carbon dioxide dissolves in water, increasing the acidity so the greater the pH, the greater the concentration of pH). This process could only be conducted in water using aquatic plants (Soria-Dengg, 2009).

Alternatively, oxygen in a product in the process of photosynthesis and so measuring the amount of oxygen produced would allow for the rate of photosynthesis to be determined (Trimble, 2019). Measuring of this factor can be conducted by counting bubbles produced (Measuring the rate of photosynthesis, 2021).

Since glucose is a product of photosynthesis, the carbohydrate production could be measured to compare weight differences between plants, representing a difference in carbohydrates (sugars) due to the reaction. This would require plants to be harvested, dried, and weighed at intervals (Trimble, 2019).

Hills reaction, which measures the light-dependent phases of photosynthesis uses dichlorophenolindophenol (DCPIP) (Trimble, 2019), an artificial electron acceptor of oxygen atoms that mimics NADP whilst undergoing a blue to clear colour change during reduction from its original form to DCPIPH, as the terminal electron acceptor of oxygen atoms. The rate of colour change from blue to clear has a directly proportional relationship to the rate of oxygen produced from chloroplasts, which can be used to measure the rate of photosynthesis since within the process of photosynthesis, water molecules are split using light energy, allow chloroplasts to produce oxygen. A spectrophotometer can be used to measure the amount of light absorbed in the solution (PHOTOSYNTHESIS: THE HILL REACTION, n.d.).

Chlorophyll fluorescence can also be used since chlorophyll molecules enter an excited state due to the absorption of light, and return to a normal state due to the release of energy. The energy released in this process in is partly used to capacitate photosynthesis, however some of this energy is also emitted as fluorescence radiation. Thus, fluorescence radiation can be deemed a complementary process to photosynthesis and its emissions can determine the rate of photosynthesis (Trimble, 2019).

Commercial instruments are also available to measure the rate of photosynthesis using other techniques:

An infrared gas analyser (figure 1) can also be used to measure the rate of photosynthesis since carbon dioxide absorbs infrared light, thus in closed environments when plants are exposed to infrared light, less carbon dioxide can be measured due to its use in photosynthetic reactions and hence, an increased level of infrared light can be measured. Infrared spectroscopy is a process that utilises this device to measure the input and output of carbon dioxide from a chamber, with the difference determining the amount of carbon dioxide used in the reaction to determine the rate of photosynthesis (Trimble, 2019).

Alternatively, an electrochemical gas sensor (figure 2) measures the presence of oxygen since it is does not absorb infrared light (Trimble, 2019). The process involves gas diffusion towards an electrode causing an electrochemical reaction (oxidation or reduction) to occur. The reaction is dependent on the gas (for example, oxygen undergoes reduction to water, whereas carbon monoxide undergoes oxidation and forms carbon dioxide). Since oxygen is the gas being analysed to measure the rate of photosynthesis, an electric current (caused by electron movement) is created that is proportional to the concentration of gas. The sensor detects the electron movement within the external circuit and determines the gas volume in parts per million. Factors such as temperature can influence electrochemical sensors and so it is suggested that temperature management is performed (How do electrochemical sensors work?, 2019).

Other devices such as a potometer (figure 3) and handheld photosynthesis systems (figure 4) can also be used to measure the rate of photosynthesis. Additionally, when measuring rates of photosynthesis measurements should be taken at the same time of the day. At 10am, maximum rates of photosynthesis occur (Trimble, 2019). It is important to ensure other factors influencing the rate of photosynthesis remain constant so that the methods above can effectively determine the reaction occurring.

The use of an electrochemical gas sensor has the ability to effectively measure the rate of photosynthesis since it is an affordable device that is accessible and is highly suited to the measurement of gas diffusion.

00Photosynthesis is a chemical reaction and hence the rate of occurrence is used to measure its efficiency. The rate of photosynthesis can be measured using various procedures and devices, including input and output monitoring techniques as below:

Commercial instruments are also available to measure the rate of photosynthesis using other techniques:

-874540-883593What effect does photosynthesis have on effective crop growth?

00What effect does photosynthesis have on effective crop growth?

6091555-888577How can the rate of photosynthesis be measured?

00How can the rate of photosynthesis be measured?

2345055-889000What tolerance limits need to be considered in weeds to grow them as an effective crop for therapeutic use?

00What tolerance limits need to be considered in weeds to grow them as an effective crop for therapeutic use?

592667104563Figure 1: Figure 2:

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Figure 3: Figure 4:

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00Figure 1: Figure 2:

Figure 3: Figure 4:

-824865356870Key:

Findings

Options

Limitations

00Key:

Findings

Options

Limitations

-850900-529167Milk thistle:

Milk thistle or Silybum marianum is a plant that contains active ingredients from a group of plant compounds known collectively as silymarin. Silymarin is mixture of three flavonolignans (silybin, silydianin, and silycistin) (Karkanis et al. 2011). Milk thistle has been used as a herbal remedy due to the high presence (65-80%) of silymarin in the milk thistle extract. Silymarin are known to contain antioxidants, as well as antiviral and anti-inflammatory properties. Due to this, it has been used to treat liver and gallbladder disorders (most researched plant for treatment of liver disease), promote breast milk production, and lower blood sugar levels (useful for diabetes management). It has also been proposed that it could be useful in treating age-related decline in brain function (has been used to treat neurological conditions such as Alzheimers), stimulate bone mineralisation to protect against bone loss, treat acne, and more (West, 2018).

This is a viable option to investigate since milk thistle can grow in a range of soil types (sandy soil to thick clay). Sowing occurs in autumn and spring, with 20-30cm between plants and 40-75cm between rows. The nutrients required for growth are quite low, considering the weed can grow in various conditions and are considered drought resistant. The main limiting factor to its growth is weed interference. Herbicides such as pendimethalin and metribuzin can be used to control this. Pendimethalin is classified as a slightly toxic compound by the US Environmental Protection Agency and is a possible human carcinogen (Hou et al. 2006). Thus, using this herbicide to increase crop growth is not safe. Furthermore, milk thistles have been modified to produce different varieties which contain varying silymarin contents (Karkanis et al. 2011). All of these factors could be trialled to test and determine the optimum conditions for photosynthesis and growth.

Nettles:

The leaves, stem, and root of stinging nettles, or Urtica dioica can be used to improve urinary tract health, support arthritis and pain, aid in blood sugar management (Moore, 2018), treat hayfever, reduce bleeding, act as a natural diuretic, and be used in wound and burn treatments. This is because the plant contains many nutrients, such as vitamins, minerals, fats, amino acids, polyphenols, and pigments. Many of these nutrients also act as antioxidants. Plants themselves contain high iron, calcium, folic acid, potassium, manganese, carotenoids, and vitamin C (Homolka, 2011). However, the plant needs to be processed before consuming and careful when handling as tiny hairs on plant release chemicals such as acetylcholine, histamine, serotonin, leukotrienes, and formic acid which can cause rashes and itchiness (Raman, 2018).

Nettles obtain water using rhizomes or underground roots, however, the plants roots are not deep and thus most of their water must be in close proximity to the plant and in the upper soil layers. Nettles also grow most successfully in nitrogen rich soil, and grow 3-7 feet high towards the Sun, allowing them an advantage over neighbouring plants as they can receive more light energy (Homolka, 2011).

Water Hyssop:

Bacopa monnieri is a semi-aquatic perennial that grows successfully in warm environments, moist soils or standing water, is fast-growing, and can grow in a wide pH range (Johnstone, 2020). Due to the presence of bacosides and presence of antioxidants, this weed has potential to reduce inflammation, improve brain function, reduce ADHD symptoms, lower blood pressure, and more. However, the use of this plant comes with numerous side effects including nausea, stomach cramps, interact with certain medications (Raman, 2019). Water hyssop is a semi-aquatic perennial, therefore alternate approaches could be used and a terrestrial option may prove more beneficial for some practicals

Altering the concentration of bicarbonate ions alters the presence of hydrogen ions, thus altering the pH. Since water hyssop can grow in a wide pH range, this will not affect the rate of photosynthesis excessively, so the influence of carbon dioxide could still be tested accurately. Also, since water hyssop can grow in water or land environments, this allows it to be effectively tested in a bicarbonate ion solution as soil is not necessarily required to influence growth. However, water temperature will need to be monitored in some way since this plant prefers warmer environments.

00Milk thistle:

Nettles:

Water Hyssop:

-852170-887519What weed has the greatest potential for therapeutic use?

00What weed has the greatest potential for therapeutic use?

4906433-884767What are the main tolerance limits for weeds?

00What are the main tolerance limits for weeds?

4906433-528107Weeds have many tolerance limits, including:

Light intensity increasing light increases the rate of photosynthesis, until another factor becomes the limiting factor (figure 5). At extremely high temperatures, the rate of photosynthesis decreases due to the denaturation of enzymes, however, these levels are not naturally occurring (Photosynthesis, 2021). The light intensity can be influenced by the distance between the plant and the source. The light intensity is inversely proportional to the square of the distance from the plant, represented by the equation I=1/r2Carbon dioxide availability if carbon dioxide concentration is increased, then the rate of photosynthesis will increase (figure 6) as carbon dioxide is a reactant (Photosynthesis, 2021). Increased atmospheric carbon dioxide concentration is thought to increase photosynthesis by reducing drought impacts, decreasing stomatal conductance, and increasing soil water content (Pathare, 2017).

Water availability If plants do not have access to sufficient water, stomata will close. For example, drought conditions (combination of low soil and water) can cause strain on the vascular system of actively growing plants. As plants water potential decreases, strain increases. This leads to tension (induced cavitation) which can be harmful to plants by disrupting transpiration stream in xylem, leading to leaf desiccation and in most cases plant death (Craine et al. 2012).

Temperature The reaction of photosynthesis is controlled by enzymes. At low temperatures, the rate of photosynthesis is low due to only having a small quantity of kinetic energy and interactions between particles (low enzyme and substrate interactions). Alternatively, at temperatures that are too high, enzymes can become denatured, meaning the rate of photosynthesis would decrease as enzymes are not able to catalyse reaction (figure 7) (Photosynthesis, 2021).

Chlorophyll Leaves with more chlorophyll can better absorb light, which is required for photosynthesis to occur (Photosynthesis, 2021).

Soil pH soil pH measures the hydrogen ion concentration in a particular soil. The more hydrogen ions present, the lower the pH (inverse relationship). The lower the pH of the soil, the greater the acidity. Generally, a pH of 6.0-7.5 is the optimum for most plants, however the optimum pH can differ for various plants (Soil pH and Nutrient Availability, 2015).

Nutrients different plants require different nutrients within their soils. Even if other nutrient concentrations are increased, if one nutrient is outside of an organisms tolerance limit, the growth rate of the plant will not increase. Nutrient availability can be affected by numerous factors, including competition from other organisms (reference textbook).

At some point, factors may become limiting and will change depending on the plant. Each factor has the ability to influence another. For example, as water availability increases, the importance of other factors such as shade and nutrient availability increase.

Other factors include herbicide resistance, seasonal variability, weather, and more.

Figure 5: Figure 6: Figure 7:

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Carbon dioxide availability would be the easiest tolerance limit to investigate since carbon dioxide is a product of photosynthesis and thus measuring its production is an effective way of testing the rate of photosynthesis. The concentration of bicarbonate ions which act as a source of carbon dioxide provide an accessible way to determine its influence since it can be easily changed and the materials are accessible and safe.

00Weeds have many tolerance limits, including:

Chlorophyll Leaves with more chlorophyll can better absorb light, which is required for photosynthesis to occur (Photosynthesis, 2021).

Other factors include herbicide resistance, seasonal variability, weather, and more.

Figure 5: Figure 6: Figure 7:

-802112796705Key: Findings Options Limitations

00Key: Findings Options Limitations

4284133-753533Risk Assessment:

Hazard Risks Precautions Taken Actions If Necessary

Glassware Cuts and injury. Breakages. Do not use broken or cracked glassware.

Handle with caution and use appropriate protective clothing, including safety glasses, lab coat, and gloves. Report all breakages to your teacher immediately. Clean immediately with appropriate equipment. Avoid contact with broken glass. In the case of injury, seek medical advice.

Calcium Bicarbonate Solution (Ca(HCO3)2).

Spills. Slipping hazard. Electrocution. May result in hypotension or lactic acidosis.

Use water over a sink or surface with drainage system.

Keep away from electrical sources Alert teacher and clean spills immediately.

Turn off power source. Seek medical advice if necessary.

Light source Electrocution. Heat burns. Cuts and injury if broken. Use equipment with caution. Ensure it is appropriately safety tested. Do not directly contact light source when on or for a while after use. Turn off power source. Rinse burns under cold water immediately. Seek medical advice if necessary.

Water hyssop May cause skin or eye irritation. High concentrations may act as anaesthetic. May cause allergic dermatitis from repeated contact. Ensure appropriate safety wear is worn. Handle with care. Dispose of safely. Rinse exposed sites. Seek medical advice if necessary.

00Risk Assessment:

Hazard Risks Precautions Taken Actions If Necessary

Glassware Cuts and injury. Breakages. Do not use broken or cracked glassware.

Calcium Bicarbonate Solution (Ca(HCO3)2).

Spills. Slipping hazard. Electrocution. May result in hypotension or lactic acidosis.

Use water over a sink or surface with drainage system.

Keep away from electrical sources Alert teacher and clean spills immediately.

Turn off power source. Seek medical advice if necessary.

-79670518107Hypothesis:

If the concentration of carbon dioxide is increased, then the rate of photosynthesis will also increase until another factor becomes limiting.

00Hypothesis:

If the concentration of carbon dioxide is increased, then the rate of photosynthesis will also increase until another factor becomes limiting.

-793750-474546Aim: To investigate the effect of carbon dioxide (represented by bicarbonate ions) on the rate of photosynthesis and therefore the growth of water hyssop.

00Aim: To investigate the effect of carbon dioxide (represented by bicarbonate ions) on the rate of photosynthesis and therefore the growth of water hyssop.

-795655-836332Experimental Design

00Experimental Design

-796705153230Experimental Variables:

Independent variable- Carbon dioxide will be varied by changing the concentration of bicarbonate ions in the following concentrations: 0.0%, 0.50%, 1.0%, 1.50%, 2.0%.

Dependent variable- Rate of photosynthesis, represented by the electrochemical oxygen sensor measuring the amount of oxygen produced.

00Experimental Variables:

Independent variable- Carbon dioxide will be varied by changing the concentration of bicarbonate ions in the following concentrations: 0.0%, 0.50%, 1.0%, 1.50%, 2.0%.

Dependent variable- Rate of photosynthesis, represented by the electrochemical oxygen sensor measuring the amount of oxygen produced.

-796413153136Controlled Variables: Variable - How Why

- Temperature hot water bottles placed between beakers to monitor temperature of solution using temperature sensors - since the temperature can influence kinetic energy and the number of successful collisions occurring in a specific time, hence influencing the rate of photosynthesis

- External light the same light source (150W reflection lamp) will be used for all trials to ensure all discs will be exposed to the same intensity and type of light

- Mass and surface area of water hyssop 2g mass will be measured using electronic balance and samples will be cut to 1cm3 area so that gas exchange occurs at even rates between discs and so same amount of water hyssop is present to react

- Pressure in beaker use three-way valve to set to atmospheric pressure at start of each trial increased pressure results in decreased rate of photosynthesis (dependent on other factors) (Takeishi et al. 2013). Ensuring pressure remains constant allows for the effect of carbon dioxide to be directly investigated.

- Type of bicarbonate ions Calcium Bicarbonate solution will be used Most soluble bicarbonate ion, meaning diffusion of gases in water can occur more effectively, rather than limiting the rate of photosynthesis.

00Controlled Variables: Variable - How Why

- External light the same light source (150W reflection lamp) will be used for all trials to ensure all discs will be exposed to the same intensity and type of light

441663647414Overall Hazard Assessment:

Low Medium-Low

Medium Medium-High High

0Overall Hazard Assessment:

Low Medium-Low

Medium Medium-High High

-795655200449Uncontrolled Variables: Variable Why

- Biological tissue Although it was avoided, some discs contained vascular tissue of the plant which is not photosynthetic, thus decreasing the number of photosynthetic cells present. Dead tissue may also be present amongst the leaf, decreasing its photosynthesising ability. Additionally, due to the surface area of discs (although the size and mass was monitored) the thickness of the leaf was unable to be monitored, which could have resulted in lower chlorophyll presence and chloroplast concentration in certain areas.

- Light exposure of individual discs Since numerous discs were placed in the same beaker, overlapping of discs occurred. This was not monitored and thus the surface area of discs exposed to the light differed. Furthermore, the location of discs in the beaker was different and hence the light intensity discs were exposed to differed due to location.

-External temperature The external temperature was not able to be monitored. While the temperature of the beaker was monitored, the external temperature may still have caused fluctuations, thus influencing the kinetic energy and collision of particles and hence rate of photosynthesis.

00Uncontrolled Variables: Variable Why

5451475-334010- 1250 mL 2% bicarbonate ion solution

- 2x 50mL test tube

- 2x rubber stopper

- 1x 150W reflective light source

- 2x 1L flat water bottles

- 2x temperature sensors

- 2x syringe extender

- 2x three-way valve

00- 1250 mL 2% bicarbonate ion solution

- 2x 50mL test tube

- 2x rubber stopper

- 1x 150W reflective light source

- 2x 1L flat water bottles

- 2x temperature sensors

- 2x syringe extender

- 2x three-way valve

3244132-842838Materials

00Materials

3244132-524786- 2x Electrochemical oxygen sensor

- 50g water hyssop

- 1x 2mm2 holepunch

- 1x ruler

- 1250mL 0% bicarbonate ion solution

- 1250mL 0.5% bicarbonate ion solution

- 1250mL 1% bicarbonate ion solution

- 1250mL 1.5% bicarbonate ion solution

00- 2x Electrochemical oxygen sensor

- 50g water hyssop

- 1x 2mm2 holepunch

- 1x ruler

- 1250mL 0% bicarbonate ion solution

- 1250mL 0.5% bicarbonate ion solution

- 1250mL 1% bicarbonate ion solution

- 1250mL 1.5% bicarbonate ion solution

-475403-247227Electrochemical oxygen sensors

00Electrochemical oxygen sensors

7541172-524510- 1x stopwatch

- 1x electronic balance

- 1000mL distilled water

- 10L water

- 2x thermometer

- 1x kettle

0- 1x stopwatch

- 1x electronic balance

- 1000mL distilled water

- 10L water

- 2x thermometer

- 1x kettle

-25349726903-796706-570368Preparation:

1. Assemble equipment as illustrated below:

INCLUDEPICTURE "https://image.isu.pub/160519081954-7e942de805d0ffff0bb7209b92034a77/jpg/page_1.jpg" * MERGEFORMATINET

a. Weigh 2g of fresh water hyssop and cut into 2mm2 pieces using holepunch. Place evenly in one test tube.

b. Pour 25mL of 0% Calcium Bicarbonate solution into each beaker.

c. Seal test tube with rubber stopper.

d. Place 2 50mL test tubes next to one another 25cm in front of the light source. Ensure both are equally illuminated.

e. Place a 1L flat water bottles between the light source and test tubes.

f. Set up the temperature sensors to monitor the temperature of water in bottles.

g. Insert syringe extender into each stopper.

h. Attach a three way valve to the end of each syringe extender.

i. Connect an electrochemical oxygen sensor to each valve.

h. Ensure both test tubes are at atmospheric pressure. Turn the three-way valves to position A then B to create atmospheric pressure.

Conduction:

1. Illuminate test tubes for 5 minutes.

2. Measure temperature in each test tube using a thermometer.

3. Record the value on the electrochemical oxygen sensor, detecting the initial concentration of gases present.

4. Allow reaction to occur for eight minutes.

5. Record the measurement from the electrochemical oxygen sensor, detecting the final amount of gas present.

6. Measure the temperature in each test tube using thermometer.

7. Calculate the amount of oxygen produced by final oxygen volume initial oxygen volume.

8. Pour out Calcium Bicarbonate solution from both test tubes and rinse test tubes with distilled water.

9. Repeat preparation method. Repeat steps 1-8 4 more times.

10. Repeat steps 9 for concentrations of 0.5%, 1.0%, 1.5%, 2.0% Calcium Bicarbonate solution.

00Preparation:

1. Assemble equipment as illustrated below:

INCLUDEPICTURE "https://image.isu.pub/160519081954-7e942de805d0ffff0bb7209b92034a77/jpg/page_1.jpg" * MERGEFORMATINET

a. Weigh 2g of fresh water hyssop and cut into 2mm2 pieces using holepunch. Place evenly in one test tube.

b. Pour 25mL of 0% Calcium Bicarbonate solution into each beaker.

c. Seal test tube with rubber stopper.

d. Place 2 50mL test tubes next to one another 25cm in front of the light source. Ensure both are equally illuminated.

e. Place a 1L flat water bottles between the light source and test tubes.

f. Set up the temperature sensors to monitor the temperature of water in bottles.

g. Insert syringe extender into each stopper.

h. Attach a three way valve to the end of each syringe extender.

i. Connect an electrochemical oxygen sensor to each valve.

h. Ensure both test tubes are at atmospheric pressure. Turn the three-way valves to position A then B to create atmospheric pressure.

Conduction:

1. Illuminate test tubes for 5 minutes.

2. Measure temperature in each test tube using a thermometer.

3. Record the value on the electrochemical oxygen sensor, detecting the initial concentration of gases present.

4. Allow reaction to occur for eight minutes.

5. Record the measurement from the electrochemical oxygen sensor, detecting the final amount of gas present.

6. Measure the temperature in each test tube using thermometer.

7. Calculate the amount of oxygen produced by final oxygen volume initial oxygen volume.

8. Pour out Calcium Bicarbonate solution from both test tubes and rinse test tubes with distilled water.

9. Repeat preparation method. Repeat steps 1-8 4 more times.

10. Repeat steps 9 for concentrations of 0.5%, 1.0%, 1.5%, 2.0% Calcium Bicarbonate solution.

-798195-840520Method: Effect of carbon dioxide on the rate of photosynthesis

00Method: Effect of carbon dioxide on the rate of photosynthesis

324413210685Justifications

00Justifications

-534154170997

324358041910- This mass will ensure the critical mass of photosynthetic cells is present in the water hyssop for the reaction to occur.

- Fresh water hyssop will be used to decrease the influence of dead tissue impacting photosynthetic cell presence.

- Water hyssop will be used since it is an aquatic weed that has photosynthetic abilities. It can grow in a wide pH range and since presence of bicarbonate ions can alter pH, this will allow reactions to still be observed in this range.

- 2mm3 discs will be used so that the surface area is the same and thus, gas exchange can occur at even rates by increasing the likelihood of having an equal biological tissue presence across trials.

- To prevent overlapping of discs in beaker so that each disc receives similar light intensities and have similar surface area exposed for reactions to occur.

- This volume is enough to submerge the amount of tested water hyssop whilst allowing the reaction to occur. This will remain the same for all trials so that the number of ions present is only influenced by concentration and not volume.

- To create an enclosed environment that is less likely to be influenced from the external environment. This will prevent oxygen and carbon dioxide from the external environment from interfering with measurements within the internal environment, so that the oxygen produced can be accurately measured, as well as reducing temperature interference.

- 2 test tubes will be used under each trial so that one can be used as the control. This will increase the accuracy of results as, for example, if beakers for different trials are placed in slightly different positions, thus receiving different light intensities, this will be noticed in control differences to reduce the impact of random errors.

- 25cm distance will remain constant as it ensures the light intensity remains constant. This is necessary since light intensity can influence the rate of photosynthesis. The light intensity can be monitored through calculations using the inversely proportional relationship between light and distance, represented by the equation I=1/r2.

- 150W reflection lamp used as light source to ensure light intensity and type of light remains constant whilst providing sufficient energy for reaction to occur.

- Since temperature can influence the kinetic energy in a reaction, thus influencing the collisions between particle and hence the reaction rate, water bottles will be used to prevent heating of the test tubes and maintain consistency in the temperature of beaker.

- Temperature sensor in water to monitor heat. If temperature rises more than 5 degrees in 5 minutes, measurements will be ceased and water in bottles will be changed.

- Ensure consistency between each trials since pressure influences the photosynthetic abilities of a species, whilst providing similar conditions that the species would naturally be subject to on Earth.

- Is highly suited to the measurement of gas (oxygen) diffusion because this device provides fast electrochemical readings with a high level of resolution, making it the most viable option for this design.

- To decrease reaction time and ensure sufficient oxygen is produced to create a noticeable change (outweigh cellular respirations consumption of oxygen) in the time allowed for the reaction to occur (eight minutes). This is because illuminating will ensure solution is saturated with oxygen and oxygen release can be measured immediately at the start of experiment, otherwise an additional six minutes can be expected before reaction occurs.

- To ensure a range is tested where the relationship between bicarbonate ion concentration and the rate of photosynthesis will be observed. Testing greater concentrations will demonstrate the point at which another limiting factor replaces carbon dioxide availability, at which point a plateau will be observed.

- Calcium Bicarbonate solution is the most soluble bicarbonate ion, meaning the diffusion of gases will occur more effectively rather than being a limiting factor for the rate of photosynthesis.

- Rinse test tubes to remove the presence of bicarbonate ions before conducting further trials, as these remnants would increase the Calcium Bicarbonate solution concentration compared to the stated concentrations.

00- This mass will ensure the critical mass of photosynthetic cells is present in the water hyssop for the reaction to occur.

- Fresh water hyssop will be used to decrease the influence of dead tissue impacting photosynthetic cell presence.

- 2mm3 discs will be used so that the surface area is the same and thus, gas exchange can occur at even rates by increasing the likelihood of having an equal biological tissue presence across trials.

- To prevent overlapping of discs in beaker so that each disc receives similar light intensities and have similar surface area exposed for reactions to occur.

- 150W reflection lamp used as light source to ensure light intensity and type of light remains constant whilst providing sufficient energy for reaction to occur.

- Temperature sensor in water to monitor heat. If temperature rises more than 5 degrees in 5 minutes, measurements will be ceased and water in bottles will be changed.

- Calcium Bicarbonate solution is the most soluble bicarbonate ion, meaning the diffusion of gases will occur more effectively rather than being a limiting factor for the rate of photosynthesis.

-796705211229Water hyssop

00Water hyssop

Report

Introduction

Photosynthesis is a process by which plants utilise sunlight, water, and carbon dioxide to produce oxygen and chemical energy within cells containing chloroplasts (figure 1). Within this reaction, water is oxidized (loses electrons) and carbon dioxide is reduced (gains electrons), thus water and carbon dioxide are converted to glucose and oxygen. Oxygen is released into the external environment and energy is stored in glucose molecules (Photosynthesis, n.d.).

Figure 1: Photosynthesis equation (Kirkpatrick, n.d.) INCLUDEPICTURE "https://www.researchgate.net/profile/Kaylyn-Kirkpatrick/publication/327920538/figure/fig1/AS:675578826989570@1538081952519/The-chemical-equation-of-photosynthesis.png" * MERGEFORMATINET 0000

This process, although containing many steps, can be divided into light-dependent and light-independent reactions. Light-dependent reactions require a continual input of sunlight in which chlorophyll absorbs energy from the light waves to convert to chemical energy, producing the storage compounds adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide phosphate (NADPH). This occurs within the thylakoid membrane of a cell, whereas light-independent reactions occur in the stroma. Light-independent reactions do not require light as the energy from the storage compounds is used to produce carbohydrate molecules (for example, glucose) from carbon dioxide (Photosynthesis, n.d.).

Organisms grow most effectively within their tolerance limits. Thus, abiotic factors can influence an organisms survival. For example, carbon dioxide availability results in an increased rate of photosynthesis since it is a reactant. Increased carbon dioxide results in greater Rubisco activity, causing increased carbohydrate content in leaves, greater starch reserves, and greater auxin biosynthesis (Thompson, 2017) which play a role in seedling growth, root elongation, gravitropism, and more (Zhao, 2014). In light-independent reactions, bicarbonate ions (produced due to dissolution of carbon dioxide in water) can be used as a source of carbon dioxide (Experiments in Biology for MultiLab, 2021). Thus, as carbon dioxide concentration increases, the rate of photosynthesis (or growth) increases until another factor limits the reaction.

Milk thistle has many medicinal properties, however numerous tolerance limits affect its growth. In this investigation, the effect of Sodium Bicarbonate (NaHCO3) concentration, representing carbon dioxide concentration, on the rate of photosynthesis will be tested by measuring the time taken for milk thistle discs to rise due to oxygen production.

Completion Method (Not assessed):

Aim- To investigate the effect of the concentration of NaHCO3 on the rate of photosynthesis.

Hypothesis- If the concentration of NaHCO3 increases, then the milk thistle leaf discs will rise at an increased rate due to the increased production of oxygen, representing an increased rate of photosynthesis.

Variables:

Independent: Concentration of NaHCO3 (0%, 0.05%, 0.10%, 0.15%, 0.20%, 0.25%)

Dependent: Rate of photosynthesis, represented by the rising of milk thistle leaf discs (seconds)

Controlled variables:

Controlled variable How it was controlled Why it was controlled

Volume of solution Measured to be 10mL for each trial conducted. Volume of solution will alter the amount of NaHCO3 ions present for reaction, thus influencing the carbon dioxide concentration.

Size of beaker 80mL beakers were used for all trials.

Same space for reaction to occur. Same exposure to light. Retain heat at similar rates.

Type of solution NaHCO3 solution was used as the source of bicarbonate ions for all trials. To ensure the concentration of bicarbonate ions could be accurately represented by the carbon dioxide concentration. Different bicarbonate ions have different solubilities and ion concentrations.

Size of hole punch Use same hole punch with same diameter (5mm) for all trials. Influence the surface area of trials. Allow different spaces for reaction to occur.

Light intensity Same light source (7W LED light source) used for all trials. To minimise light fluctuation to allow consistent rates of photosynthesis. Provide similar exposures to light intensity and type for all trials.

Plant type Milk thistle was used as the source for leaf discs for all trials. Different plants have different tolerance limits, respond to carbon dioxide differently, and have different rates of photosynthesis.

Detergent One drop of detergent was added to all trials. To minimise surface tension and reduce formation of gas bubbles on disc surface consistently.

Distance for discs to rise Same volume of solution was placed in the same size beaker to ensure distance from the base of the beaker to the top of solution was constant. The time taken for discs to rise is dependent on the distance they are required to rise. Hence, if the distance is the same for all trials, the rising times can be accurately monitored.

Uncontrolled variables:

Uncontrolled variable Why it needs to be controlled

External temperature The external temperature was not able to be maintained and thus fluctuations may have interfered with the temperature of trials. Temperature influences the rates at which reactions occur.

Biological tissue Although it was avoided, some discs contained vascular tissue of the plant which is not photosynthetic, thus decreasing the number of photosynthetic cells present. Dead tissue may also be present amongst the leaf, decreasing its photosynthesising ability.

State of stomata Transfer of gases (carbon dioxide and oxygen) occurs into and out of the stomata. If stomata are closed, then a lower volume of gases will diffuse into the cell resulting in a decreased rate of photosynthesis compared to when a greater number of stomata are open, creating possible inconsistencies between trials.

Materials:

Milk thistle

1x Thermometer

5 x 80 ml Beakers

2 x Plastic Syringes

1 x Distilled water

1 x Detergent dropper bottle

1 x 5mm diameter hole puncher

Plastic forceps

50mL each of (0.05%, 0.1%, 0.15%, 0.2%, 0.5%) NaHCO3 solution

7W LED light source

Method:

Preparation:

Fill a beaker (80ml) with 10ml of 0.05% NaHCO3 solution. Using a thermometer, take the initial temperature of the solution.

Add one drop of detergent to the NaHCO3 and stir gently.

Preparation of the Leaf Discs:

Using a hole puncher, hole punch 15-20 leaf discs. Avoid major leaf veins.

Remove the plunger of a syringe and place 10 leaf discs into the barrel of the syringe.

Replace the plunger and push on the plunger until only a small volume of air and leaf disc space remain in the barrel

Pull a small volume of NaHCO3 into the syringe and tap the syringe to suspend the leaf discs in the solution

Holding a finger over the syringe-opening, draw back on the plunger to create a vacuum. Hold this vacuum for about 15 seconds and while holding the vacuum, swirl the leaf discs to suspend them in the solution

Release the vacuum. The bicarbonate solution will infiltrate the air spaces in the leaves, causing the leaf discs to sink.

Repeat steps 5-6 for approximately two-three more times. Add a few more drops of detergent if the discs do not sink after three evacuations.

Remove the plunger and pour the leaf discs and solution into the beaker and place under a lamp.

Conduction:

Start the timer and record the time taken for each leaf disc to rise to the surface of the NaHCO3.

Repeat steps 2-10 two more times with 5 new leaf discs each trial.

Repeat the method using NaHCO3 concentrations of: 0.1%, 0.15%, 0.2% and 0.5%

The graphed results will be based on the point at which 50% of the disks reached the surface of the solution known as ET50. Since ET50 provides an inverse relationship between the rate of photosynthesis and concentration, 1/ET50 will be used to provide a correct representation of the relationship between these two variables (Steucek et al. 1985).

Risk assessment:

Hazard Risks Precautions taken Actions if necessary

Glassware Cuts and injury. Breakages. Do not use broken or cracked glassware.

Handle with caution and use appropriate protective clothing, including safety glasses, lab coat, and gloves. Report all breakages. Clean immediately with appropriate equipment. Avoid contact with broken glass. In the case of injury, seek medical advice.

Detergent Skin corrosion/

irritation. Eye damage. Slipping hazard. Wear appropriate safety wear. Wash exposed skin after handling. Keep away from power sources. Clean spills immediately. Seek medical advice if necessary.

Light source Electrocution. Heat burns. Cuts and injury if broken. Use equipment with caution. Ensure equipment is appropriately safety tested. Do not directly contact light source when in use or whilst radiating heat after use. Turn off power source. Rinse burns under cold water immediately. Seek medical advice if necessary.

Sodium Bicarbonate Solution (NaHCO3) Eye and skin irritation. Ensure appropriate safety wear is always worn. Avoid using high concentrations. Rinse immediately if contacted. Seek medical advice if necessary. Remove contaminated clothing and wash thoroughly.

Overall Hazard Assessment:

Low Medium-Low

Medium Medium-High High

Results

Table 1.1: Raw data Effect of NaHCO3 concentration on the rate of disc rising

Sodium Bicarbonate Solution (NaHCO3) (%) Disc rising time (sec) ET50 (sec) 1/ET50 (arbitrary units)

Trial 1 2 3 4 5 6 7 8 9 10 0.00 n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a n/a

0.05 758 802 808 855 898 938 962 998 1024 1066 9.18E+02 1.09E-03

0.10 865 985 999 1022 1030 1053 1068 1140 1204 1242 1.04E+03 9.60E-04

0.15 256 358 456 567 612 631 733 756 890 1052 6.22E+02 1.61E-03

0.20 143 143 259 266 286 297 311 319 345 368 2.91E+02 3.43E-03

0.25 300 301 315 321 326 369 416 436 451 461 3.48E+02 2.88E-03

Calculation of ET50:

Calculate median: median=trial 5+trial 62Eg. 0.05% trial median=898+9382=918 seconds

The above procedure was completed for all concentrations.

-51036322985500Figure 2: The Effect of NaHCO3 Concentration on the Rate of Photosynthesis (ET50)

Calculation of 1/ET50:

1/ET50 is the inverse of ET50.

For example, ET50 0.05% = 1918 arbitrary units

The above procedure was completed for all ET50 values.

Figure 3: The Effect of NaHCO3 on the Rate of Photosynthesis (1/ET50)

-56388018859500

Discussion

Analysis

Figure 2 displays ET50, which is the time taken for 50% of leaf discs to float to the surface of the solution, thus being a more reliable and accurate indicator of the rate of photosynthesis. However, this provides an inverse relationship since as NaHCO3 concentration increases, the rate of photosynthesis decreases (Robinson-Brown, 2017).

Figure 3 displays 1/ET50 which is used to show the proper relationship between the concentration of NaHCO3 and the rate of photosynthesis, since the trendline shows a directly proportional relationship that results in a positive slope.

Both graphs show the greatest rate of photosynthesis occurs at the 0.20% concentration (1/ET50 rate is 3.43x10-3), which is considerably higher than expected, considering it is located significantly above the trendline. The lowest rate of photosynthesis occurs at the 0.10% concentration (1/ET50 rate is 1.04x10-3) whilst considering that at the 0.00% concentration, no reaction was observed within a 50-minute time interval. The trendline in Figure 3 suggests that as the NaHCO3 concentration increases, the rate of photosynthesis also increases, although the data points do not show this directly.

382905099110300The R2 value in Figure 3 represents a 74.99% accuracy. Theoretically, since bicarbonate ions act as a source of carbon dioxide in this reaction, as the concentration of NaHCO3 ions increases, the rate of photosynthesis should increase as carbon dioxide is a reactant. Due to an increased reactant concentration, more oxygen is produced (product), creating the buoyancy of the disc and allowing it to rise (Figure 4). Thus, if discs rise at a faster rate this shows increased oxygen production, representing a greater rate of photosynthesis. Therefore, it can be observed that the 0.20% concentration exhibited the highest oxygen production, whereas the 0.10% concentration exhibited the lowest oxygen production.

3829050784363Figure 4: Effect of carbon dioxide concentration on oxygen production in disc rising (Elbiology.com, n.d.)

Figure 4: Effect of carbon dioxide concentration on oxygen production in disc rising (Elbiology.com, n.d.)

This increase will occur until another factor limits the reaction, which is not effectively shown in Figure 2 and 3 since after a dramatic increase in the rate of photosynthesis for the 0.20% concentration, a decrease is observed for the following 0.25% concentration. If carbon dioxide concentration was no longer the limiting factor, the rate should have remained constant.

Evaluation

Random:

Cellular respiration occurring within the leaf samples requires an input of oxygen, thus consuming some of the oxygen produced from photosynthesis. This would have affected data by increasing the rising time since discs would require a longer time to obtain enough oxygen to float, thus decreasing the perceived rate of photosynthesis. There is no way to easily quantify the rate of cellular respiration between cells. Cellular respiration is influenced by multiple factors such as water content and temperature. Thus, since the aqueous content was influenced by mixing with differing volumes of hot water in beakers to increase the temperature, this would have altered the water content as the volume of solution was not directly monitored. Additionally, the temperature of the external environment was not monitored and may have influenced the kinetic energy between molecules in the solution, thus impacting the rate of photosynthesis. This could account for the low precision in Table 1, particularly within the 0.15% concentration with some trials having an extremely fast rising time (256 sec) and others having longer rising times (1052 sec), thus showing a broad range whilst creating a lower overall 1/ET50 value. To prevent this, a hot water bath could be used to maintain the temperature at a constant value or the trials could be conducted in a temperature-regulated environment.

Variability was observed in the amount of oxygen that is contained in the leaf after production. Each individual disc produces a different amount of oxygen and different amounts of this oxygen are dislodged from the leaf, observed by rising bubbles. For discs to rise, a sufficient amount of oxygen must remain in the leaf and thus, when oxygen is dislodged, a longer time is required to produce more oxygen before it is able to rise. This could account for the larger rising times, particularly within the 0.10% concentration, producing a greater lower 1/ET50 value.

Systematic:

Carbon dioxide diffuses across mesophyll in a complex process that is influenced by aquaporins, chloroplast distribution, and cell wall thickness. The environmental conditions leaves are exposed to prior to the trials may have been different, thus affecting their quality. Due to this, chlorophyll may not be consistently present in high quantities and damage to leaves may influence surface area, influencing factors above. Furthermore, carbon dioxide enters through stomata and move toward the interior of the chlorenchyma cells where chloroplasts transform light energy. If a larger number of stomata are closed, this process would not occur as efficiently (Yahia, 2019) and result in a decreased rate of photosynthesis. To reduce the effect of this error, leaves could be grown in a controlled environment and the stomatal density could be considered.

The quality of the light source would have affected the rate of photosynthesis for all trials due to the amount of light intensity provided for the reaction to occur. Whilst the indicated intensity of each globe was 7W, calibrations may not have been accurate. For example, if a lower light intensity was produced for all trials this would have resulted in a suboptimal rate of photosynthesis. Furthermore, photosynthesis occurs best in particular wavelengths of light. The photon energy is inversely proportional to the wavelength, thus, if a low-quality light source produced a lower light intensity hence producing wavelengths closer to the green colour, a decreased amount of light could be absorbed by the discs. Within the practical, the wavelengths of light being produced from globes were not measured. Natural lighting would provide alternate wavelengths to the artificial source use and thus produce different rates of photosynthesis. Due to the presence of chlorophyll, red (600-700nm) and blue (425-450nm) wavelengths are best absorbed.

A factor that could not be controlled was that although major vascular tissue present within the veins of the plant were avoided, smaller veins in the leaves could not be. Different quantities of the vascular tissue were present in each trial due to this. Vascular tissue does not contain photosynthetic cells and thus, discs with greater quantities of vascular tissue would have had decreased photosynthetic abilities, causing a decreased rate of photosynthesis (and vice versa). For example, the 0.10% concentration could have experienced this effect due to the observation of some trials having significantly slower rising times. Increasing the sample size by increasing the number of trials would increase the precision of results.

Conclusion

This practical partially supports the hypothesis, due to the identification of numerous errors. This is shown as Figure 3 suggests that the 0.20% concentration has the greatest rate of photosynthesis due to its decreased rising times, rather than increasing at a constant rate until the presence of another limiting factor can be observed, demonstrating the low accuracy of data. To improve, factors discussed above would need amending. This investigation is limited, as the results are only relevant for impacts of NaHCO3 concentration on milk thistle leaves. To generalise conclusions, it is necessary to complete subsequent practicals testing various plant species and a broader NaHCO3 concentration range.

Word count: 1500

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