QUEENSLAND ACADEMY FOR HEALTH SCIENCES INTERNATIONAL BACCALAUREATE Term 1 2013 SUBJECT: BIOLOGY YEAR 11 HL & SL Name of Student: Name of Teacher: FORMATIVE ASSESSMENT ITEM: Chemistry of Life Practical Investigation Term 1 Task: Investigation of a Factor Affecting Enzyme ActionAspects Assessed: D DCP CE MS Introduction:Thousands of enzymes are found in living cells. In addition to making life possible, many enzymes have numerous applications that affect our daily lives in other ways such as food processing, clinical diagnoses, sewage treatment, and the textile industry.
In this activity you will investigate how a particular factor influences the action of an enzyme. Conditions: Students are NOT required to design an experiment. Experimental design has been provided for you to use instead. You are however required to submit a Risk Assessment for the investigation. Students are to work independently. However, you will need to collect raw data from 4 other students to make the 6 trials. The final version is to be submitted to TURNITIN and then class teacher. A journal will need to be included as part of the final submission.
Time Allowed: 4 weeksDue Dates Task Out first lesson week1, term 1, 2013Risk Ass Due: last Lesson week 2, Term 1, 2013Final: First lesson week 6, Term 1, 2013Procedure: Your task is to investigate the effect of temperature on the activity of enzyme catalase found in beef liver. Use the experimental design and the BioLab Guide provided to assist with your report write up.
Safety Considerations:You must have the risk assessment checked before continuing. NOTE: For this task you are required to submit a journal which documents your progress. You are also required to include photographs which display the techniques you used in the experimental procedures. This evidence will be used in assessing your manipulative skills in this experiment| RESULTS: REFER TO the Assessment Grading Matrix| Effect of temperature on the activity of Catalase Design Aspect 1: Research Question
This lab will be driven by the research question, Do changes in temperature (from 0? C, 7? C, 19? C, 37? C, and 100? C) have an effect on the activity of the enzyme catalase (found in beef liver) in the breakdown of hydrogen peroxide? Hypothesis If liver is placed in different temperatures of 0? C, 7? C, 19? C, 37? C, and 100? C and hydrogen peroxide is added to each piece of liver, then the liver placed in 37? C will have the largest reaction height. The liver in 100? C will have the smallest reaction height, followed by the liver in 0? C, then 7? C, and then 19?
C. Introduction Pearson Baccalaureate: Standard Level Biology Developed Specifically for the IB Diploma defines enzymes as “protein molecules which act as catalysts for reactions. As catalysts, the real function of enzymes is to lower the activation energy of the reactions that they catalyze” (166). Enzymes are proteins; therefore the liver has a particularly high concentration of catalase. When hydrogen peroxide (H2O2) is added to liver, catalase catalyzes a reaction in which the hydrogen peroxide is broken down into oxygen gas (O2) and liquid water (H2O).
Hydrogen peroxide is a toxic chemical that is produced as a byproduct of many normal cellular reactions, so it is crucial that catalase in the liver breaks the hydrogen peroxide down into the two harmless substances of oxygen gas and liquid water. The hydrogen peroxide must be quickly degraded or converted, and catalase accomplishes this task because one molecule of catalase can deal with six million molecules of hydrogen peroxide in one minute. Enzymes and the temperature of their environment are particularly important to the human ody because “Many of the reactions which represent the digestive process would need far higher temperatures than we are able to maintain safely if enzymes were not involved” (166). The prediction in the hypothesis is based on the concept of denaturation. As Pearson Baccalaureate: Standard Level Biology Developed Specifically for the IB Diploma states, “Reactions which use enzymes do have an upper limit. That limit is based on the temperature at which the enzyme (as a protein) begins to lose its three-dimensional shape due to intramolecular bonds being stressed and broken.
When an enzyme loses it shape, including the shape of the active site, it is said to be denatured” (75). Due to denaturation, the liver placed in 100? C will have the smallest reaction height because at this temperature catalase will begin to denature. Because “reactions with or without enzymes will increase their reaction rate as temperature (and thus molecular motion) increases”, the liver placed in 0? C, 7? C, and 19? C will have small reaction heights, but the heights will increase as temperature increases (75). The liver placed in 37?
C will have the greatest reaction height because “human catalase works at an optimum temperature of 37? C, which is approximately the temperature of the human body”. Although this lab is using beef liver instead of a human liver, the optimum temperature for beef liver should be similar to that of humans. The predictive graph on the previous page represents how as the temperature of beef liver originally increases, the height of the reaction increases as well due to an increase in molecular collisions. At a certain temperature, the catalase will reach its optimum temperature and have the greatest height of reaction.
However, as the temperature continues to increase the enzyme will begin to lose its shape and denature, so the height of the reaction will decrease. This lab will be using beef liver, which contains the specific enzyme catalase, and by placing the liver into different temperatures it will be assessed how catalase performs under certain conditions. After the liver has been placed in different temperatures, hydrogen peroxide will be added to each piece of liver, and by measuring the height of the chemical reaction it will be determined which temperatures catalase performs the best in.
Reactions with a high height will represent catalase quickly and efficiently breaking down the hydrogen peroxide, and reactions with a low height will represent catalase slowly and inefficiently breaking down the hydrogen peroxide. This lab will serve as a model for the role of enzymes in the human body, and will outline the importance of enzymes for the human body. Independent Variables The independent variable is the temperature of the liver, and it will be measured in ? C. The different temperatures used will be 0? C, 7? C, 19? C, 37? C, and 100? C. Dependent Variables
The dependent variable is the height of the reaction, and the bubbles of gas produced will be measured in millimetres (mm). Control Variables Table 1: Control variables and their treatments Variable | Effect | Control | Size of liver | Could increase or decrease the height of the reaction. A larger piece of liver means more catalase, which could break down the H2O2 at a more efficient rate than smaller pieces of liver. | Cut every piece of liver the same size by weighing each piece on an electric beam balance. Each piece of liver is approximately 1. 4g. pH | pH has an effect on enzymes and each enzyme has an optimal pH. By making the liver more acidic, basic, or neutral the height of the reaction could increase or decrease as it deviates from its optimal pH. | Do not change the pH of any of the solutions. This lab is only investigating the effect of temperature on enzyme activity, not the effect of pH on enzyme activity, so nothing should be added to the liver that would increase or decrease the pH. | Time | If some pieces of liver are kept in their specific temperatures longer than others, the height of the reaction could be greatly affected.
By keeping the liver in its temperature for a shorter period of time, the liver itself has less time to change temperature which could greatly alter the results. | Keep all of the pieces of liver in their specified temperatures for five minutes. | Size of test tube| Different sized test tubes will hold different volumes of O2 and will give incorrect measurements with the ruler| Keep all the test tubes the same size – with volume of 30cm3| Uncontrolled Variables The variables that will be difficult to control include air pressure in the lab and the volume of the liver.
Measures will be taken to reduce the effect of these on the experiment by keeping air conditioning at 24? C and cutting the liver close to the same shape and size. Control Experiment The control experiment for this investigation will be the experimental setup at 0? C. All the steps in the method will be followed at this temperature. At 0? C the experiment should not proceed as the energy needed for enzyme action is unavailable. Design Aspect 2: Materials and Equipment Needed 10 Test Tubes 1 Package of Beef Liver 2 250mL Beakers 2 Test Tube Racks 1Forceps 1 Hot Plate 1LIce 1 Plastic Bin 20 mlHydrogen Peroxide 100 mL Beaker 1 10mL Graduated Cylinder 5 Thermometers 1 Sharpie 1 Electronic Beam Balance 1 Knife Method 1. Prepare an ice bath by placing ice into a container, and place a thermometer into the ice bath. Wait until the temperature has reached 0? C. 2. Prepare two more water baths like this at 7? C and 19? C. (You can replace these two temperatures with that of the fridge and room) 3. Prepare a hot water bath by placing a 250mL beaker filled with water on a hot plate, and place a thermometer into the water. Wait until the temperature has reached 100? C. You can use and electric water bath if one is available. . Prepare a warm water bath by placing a 250mL beaker filled with water on a hot plate, and place a thermometer into the water. Wait until the temperature has reached 37? C. You can use and electric water bath if one is available. 5. Obtain beef liver and cut the liver into 10 slices which are approximately the same size. Weigh each slice on an electronic beam balance to ensure they are the same weight. 6. Obtain 10 test tubes and place them into a test tube rack. Label 5 test tubes with a number from 1-5, and repeat for the remaining five test tubes. 7. Obtain 15mL of hydrogen peroxide and a graduated cylinder. . With forceps, place a piece of liver into each of the test tubes. 9. After the liver has been placed in the test tubes labelled 3, place a thermometer into the test tube rack and wait for 5 minutes. After 5 minutes, pour 2mL of hydrogen peroxide into each of the test tubes, observe the reaction, and label the height of the reaction after 1 minute with a Sharpie. (This is the experiment at room temperature. If you have prepared a water bath at 19? C then use it instead). 10. Remove both of the test tubes labelled 1 from the test tube rack, place them in the ice bath, and wait for 5 minutes.
After 5 minutes, remove the test tubes from the ice bath, add 2mL of hydrogen peroxide into each of the test tubes, observe the reaction, and label the height of the reaction after 1 minute. 11. Remove both of the test tubes labelled 2 from the test tube rack, place them in a different test tube rack and place this rack into the fridge. Place a thermometer into the fridge as well. Wait for 5 minutes, and then read the temperature of the fridge and remove the test tubes. Pour 2mL of hydrogen peroxide into each of the test tubes, observe the reaction, and label the height of the reaction after 1 minute. If you have prepared a water bath at 7? C then use it instead). 12. Remove both of the test tubes labelled 4 from the test tube rack, place them in the warm water bath (37? C), and wait for 5 minutes. After 5 minutes, remove the test tubes from the warm water bath, add 2mL of hydrogen peroxide into each of the test tubes, observe the reaction, and label the height of the reaction after 1 minute. 13. Remove both of the test tubes labelled 5 from the test tube rack, place them in the hot water bath (100? C), and wait for 5 minutes. After 5 minutes, remove the test tubes from the hot water bath, add 2mL of ydrogen peroxide into each of the test tubes, observe the reaction, and label the height of the reaction after 1 minute. 14. With a ruler, measure from the bottom of the test tube to the mark which labels the maximum height of the reaction after 1 minute. Repeat this for all 10 test tubes, and record the measurements in your data table. 15. Pour the liver from each test tube into a waste beaker, clean each of the test tubes out, and put all materials away. 16. Combine the data that your own group obtained with the data from two other groups.
This will allow for six trials worth of data, and once you obtain this sufficient amount of data, calculate the average height of the reaction for each of the five temperatures over the six trials, and then calculate the standard deviation for each of the five temperatures over the six trials as well. Variable | Unit of Precision | Error/Uncertainty | Temperature | ? C | +/- 0. 5? C | Height | mm | +/- 0. 5mm | In the procedure, the maximum height of the reaction will be determined by marking the position of the tallest bubble that results from the reaction. Practical Safety and Risk Assessment
All care will be taken when dealing with hot plate and hot water to prevent burning and scalding. The knife and glassware will be used carefully and hand gloves will be worn when handling hydrogen peroxide. Note the following hazards with hydrogen peroxide: Contact with eyes can cause serious long term damage. The solution is corrosive and can cause skin burns. For eye contact, immediately flush eyes with plenty of water. For skin contact, wash off with plenty of water. Liver | 15 ml of Hydrogen peroxide | Liver | 15 ml of Hydrogen peroxide | Setup Diagram Design Aspect 3 Sufficiency of Data
This lab will be investigating the effect of temperature on the activity of the enzyme catalase. In this lab, five different temperatures will be investigated (0? C, 7? C, 19? C, 37? C, 100? C). Each temperature will have six trials, and this will ensure the reliability of the data. With the sufficient data, the standard deviation and mean will be calculated for each temperature. The rate of reaction at the different temperatures will also be calculated. DCP Aspect 1: Results – Raw Data Table 2: (Insert Title) | Height of Reaction| Temperature | | | | | | | 0. 0 | | | | | | | 7. 0 | | | | | | | 19. 0 | | | | | | | 37. | | | | | | | 100. 0 | | | | | | | Insert data with all units and uncertainties. Ensure decimals of the raw data and the uncertainty is the same. Highlight your own data. Note: The highlighted data is the data obtained by me. The rest of the data has been collected from (insert names). Qualitative Observations: In a paragraph answer the following questions: What happens after adding hydrogen peroxide to each of the test tubes? Discuss size of bubbles, fizz, shape of liver, etc. Did you see any colour change? Include at least 2 photographs (clear, preferably in colour) with commentary as evidence of your observations.
DCP Aspect 2: Processing Data Table 3: Statistical Processing – The following sample calculations will be done for the raw data Statistical Analysis| Formulae| Meaning of Symbols| Sample Calculation| Mean| | The mean or averagesum of sample measurements number of samples | = | Statistical Analysis| Formulae| Meaning of Symbols| Sample Calculation| Standard Deviation| | S = standard deviationx = each individual valueX = mean of all measurements= deviation from mean = degrees of freedom| Calculated in Microsoft Excel(show Excel screen clip)| Rate of Reaction| | | |
Complete this table Table 4: (Insert Title) | Height of Reaction| | | Temperature | Trial 1 | Trial 2 | Trial 3 | Trial 4 | Trial 5 | Trial 6 | Average Height of Reaction | Standard Deviation (mm +/- 0. 5mm) | Rate of reaction(mm/min +/- 1. 0)| 0. 0 | | | | | | | | | | 7. 0 | | | | | | | | | | 19. 0 | | | | | | | | | | 37. 0 | | | | | | | | | | 100. 0 | | | | | | | | | | Insert data with all units and uncertainties. Ensure decimals of the raw data and the uncertainty is the same. DCP Aspect 3: Presentation of Processed Data
Graph 1: (Insert title) Draw a graph of temperature vs. average height of reaction. Ensure to include the title, labels and scales of axes, units and uncertainties, vertical error bars and line of best fit (if applicable). Write up to 4 sentences commentary under the graph outlining the trend. State what the error bars represent. Graph 2: (Insert title) Draw a graph of temperature vs. rate of reaction. Ensure to include the title, labels and scales of axes, units and uncertainties, vertical error bars and line of best fit (if applicable).
Write up to 4 sentences commentary under the graph outlining the trend. State what the error bars represent. CE Aspect 1: Conclusion The results obtained from this lab support/reject my hypothesis. My hypothesis was: (state hypothesis here). By viewing the average height of the reaction, these results are supported/rejected. The liver placed in 37°C had an average reaction height of (state) mm, (also state the average reaction heights of the other experimental setups). This data coincides/differs with the predictions stated in the hypothesis, where I stated “The liver in 100?
C (complete). ” By observing the constructed graph in Introduction, it is clear that the average height of the reaction initially increased as the temperature increased, but when temperatures increased past optimum (37°C), (complete). Graph 1 constructed from the obtained data shows (discuss Graph 1). Graph 2 shows (discuss Graph 2). These results outline the effect of temperature on enzyme activity, and it is apparent that changes in temperature do/do not have an effect on the enzyme catalase. Conclusion Explanation
The results obtained give increased insight into the role of enzymes in the human body. The beef liver closely modelled the human liver, and it is clear that catalase works best at an optimum temperature of (state). This is important because humans maintain a stable body temperature of (state), and with the aid of enzymes this temperature provides enough activation energy for metabolic reactions, in this case the breakdown of hydrogen peroxide into oxygen gas and liquid water. (Discuss why the liver placed in lower temperatures and 100°C did not react well.
Remember to cite the references used correctly). CE Aspect 2: Evaluation: Reliability While the results obtained from this lab clearly support/reject my hypothesis, the examination of the calculated standard deviation for each temperature (discuss STDEV). This range in standard deviation is due to errors that may have occurred throughout the lab. The liver placed in 0? C had a standard deviation of (sate), the liver placed in (discuss other STDEV’s). The larger the standard deviation, the less/more reliable the data. Also discuss error bars and number of trials. Note: larger error bars = less reliable data; more trials = more reliable data). Errors/Limitations in Experimental procedure List as many errors you think may have occurred in the experimentation – from measurement as the reaction was slow, to timing, to others you can think of (preferably 5). Discuss how each of the errors could have affected your data. Significance Write a paragraph on how much the errors listed above could have impacted on your experiment’s reliability. CE Aspect 3: Suggestions for Improvements:
For each of the errors mentioned above (about 5) suggest what can be done to improve this experiment in the future. Also state how these improvements will help. References Damon, Alan, Randy McGonegal, Patricia Tosto, and William Ward. Pearson Baccalaureate: Standard Level Biology for the IB Diploma (Pearson International Baccalaureate Diploma: International Editions). n/a: Imprint Unknown, 2008. Print. “Effect of Catalase on Hydrogen Peroxide. ” http://www. sciencegeek. net/Biology/biopdfs/Lab_Catalase. pdf. (25 Jan. 2013). (Add your own references)
Delivering a high-quality product at a reasonable price is not enough anymore.
That’s why we have developed 5 beneficial guarantees that will make your experience with our service enjoyable, easy, and safe.
You have to be 100% sure of the quality of your product to give a money-back guarantee. This describes us perfectly. Make sure that this guarantee is totally transparent.Read more
Each paper is composed from scratch, according to your instructions. It is then checked by our plagiarism-detection software. There is no gap where plagiarism could squeeze in.Read more
Thanks to our free revisions, there is no way for you to be unsatisfied. We will work on your paper until you are completely happy with the result.Read more
Your email is safe, as we store it according to international data protection rules. Your bank details are secure, as we use only reliable payment systems.Read more
By sending us your money, you buy the service we provide. Check out our terms and conditions if you prefer business talks to be laid out in official language.Read more