Biology Lab Report Manual - Lakewood High School



5410200-35814000How to Write Biology Lab Reports“The science laboratory…is where humanity grows greater, stronger & better.” -- Microbiologist Louis PasteurIn some labs we observe nature; in others, we investigate cause-and-effect relationships. To look for cause-and-effect, we do an experiment. In an experiment, the independent variable [IDV] is the variable we manipulate (the “cause”). The dependent variable [DV] in the experiment is the variable we measure to see if it responds (“the effect”). Before a lab…PRE-LAB! ALL PRE-LABS ARE TYPED!!Complete a TYPED “Pre-Lab”. Your pre-lab is what you use to perform the lab. It generally has 6 parts:1.Title of the lab. BE SPECIFIC and keep it simple “The Effect of [IDV] on [DV]”.2.Research Question: State precisely and clearly what it is that you will investigate by doing the lab. If doing an experiment, ask “What is the effect of [IDV] on [DV]?” For observation labs, just ask the question naturally.3.Hypothesis & Explanation: For experiments, propose a relationship between the DV and the IDV & make a prediction about that relationship. Then explain the rationale for your idea by CITING A SOURCE FROM A REPUTABLE WEBSITE!!!. Example: “IF [gas mileage] is related to [tire pressure] AND [for the next month the car’s tires will be properly inflated], THEN [the overall gas mileage will increase]. “According to an article in AAA Colorado magazine (PROPERLY CITE!!) about fuel economy…” 4.Variables Table: Good experimental design requires the control of variables that may affect the outcome of your experiment. Create and fill out a table such as this: (each experiment has its own number of relevant variables!)Relevant VariablesWhy Variables Might Affect the Outcome of the ExperimentHow Your Method Allows for the Control of (Holds Constant) the Relevant VariablesXYZ5.Methods/Procedures: List materials needed for the experiment. BE EXPLICIT and BE SPECIFIC about materials required; precise sizes, precise amounts needed, etc… List directions into a numbered sequence of clear steps that show what actions to take and the order in which to take them. Identify procedural wait time (if any), and include steps that can be initiated while waiting. Someone should be able to replicate your experiment without any questions about your procedures and materials used!6.Data Collection: Construct one or more TYPED, neat, ready-to-use tables for quantitative data (data in the form of numbers). Remember to follow conventional rules when making tables. Data can also be qualitative, such as a color change in a test tube or the reaction of a cell under the microscope. You’ll sketch that type of data. √Your pre-lab will be checked before we do the lab. Only well-prepared students with complete pre-labs earn the opportunity to work in the laboratory; all others will be excluded from the lab to perform classroom service.During a lab…Make the observations and/or perform the experiment. Record your data in the table you made. If you change anything (on purpose or accidentally!), make a note of it. The ability to work cooperatively and safely may also be assessed.After a lab…Complete the lab report by adding the final three necessary components:7.Data Processing & Presentation (MUST BE COMPUTER-GENERATED): Transform, analyze, and present the data in a new way to effectively communicate what you discovered. Should you average data? Draw a line of best fit on a graph? Either way, if calculations are performed, show sample calculations! Now construct a graph with it (bar, line, or pie, as appropriate). DO NOT GRAPH RAW DATA (UNPROCESSED DATA)!! 8.Conclusion: Assume the reader is a science-minded, well-educated layperson. Conclusions have four parts:a.Restatement of the question and hypothesis.b.Accurate summary of the results from the lab. Tell us what happened using actual data from your experiment in your account. This should be a good paragraph or two. c.Interpretation of the results -- your judgment as to whether the data do or do not support the hypothesis.Identification of at least three relevant sources of inaccuracy (limitations, weaknesses, or errors) and how they may have affected your data. How was the design fundamentally flawed? Don’t just use HUMAN ERROR! d.Summary statement about the validity of your conclusions based on your analysis.9.Works-Cited Page: Follow the format given belowWorks Cited in APA Format (For fields in Natural Sciences)A professional lab report always includes outside information to support your hypotheses and claims. Your references should DIRECTLY address your statement; it should not be a useless placeholder. Any factual statement you put in your paper will most likely require the IN-TEXT CITATION format. Also include the full reference in a Works-Cited Page at the end of your lab report.193929071818400right68008400-89535673735Example of Reference on a WORKS CITED PAGE: Barnwell, P. (2014, April 22). My Students Don’t Know How to Have a Conversation. Retrieved from of IN-TEXT CITATION:-22860464820“According to an article from The Atlantic (Barnwell,2014), students’ reliance on screens for communication is distracting from their ability to engage in real-time talk”.Example of a Lab Report Rubric in BiologyLab Title: …………………………………………… Name…........................................... Block….RESEARCH QUESTION W/HYPOTHESIS & EXPLANATION DATA PROCESSING & PRESENTATIONSCOREDESCRIPTION20All necessary aspects are fulfilled (see below). Exceptionally well-written, professional tone, free of writing convention errors. 17Clear and complete research question. Hypothesis and explanation fully explained and references properly cited.15Any of above underdeveloped and/or missing. 12Missing more than one part of the necessary aspects.VARIABLES TABLESCOREDESCRIPTION20ALL relevant variables identified and controlled. All necessary aspects are fulfilled (see below).17MOST relevant variables identified and controlled. Table is numbered with clear title. Method for controlling variables clear and correct. Explanations for why variables important clear and concise.15Most relevant variables identified and controlled. Explanations for how and why incomplete or lacking.12Missing more than 2 critical relevant variables.MATERIALS AND PROCEDURESSCOREDESCRIPTION20Exceptionally well-written and the reader would not need to make ANY inferences using this procedure.17All specific materials and amounts needed are listed. Reader could reliably do lab following this procedure without having to make inferences.15Materials needed are listed but unclear. A few steps are vague or confusing, requiring reader to make inferences if trying to use this procedure.12Missing KEY steps or materials. Could not reliably replicate lab with this methods section.DATA COLLECTIONSCOREDESCRIPTION20All necessary aspects are fulfilled (see below). Exceptionally well-formatted, professional appearance.17All data are recorded accurately & TYPEDHas table number & clear, informative title with Table #.Column & row headings have quantities & units, with proper labels.IDV and DV are in appropriate columns, trials fitted appropriately.15All data are recorded, but minor flaws, shortcuts or inconsistencies lead reader to question some aspect of the data. 12Missing some data, and/or major flaws in execution make table misleading/incomprehensible.SCOREDESCRIPTION20All necessary aspects are fulfilled (see below). Exceptionally well-formatted, professional appearance. NO 3-D bars!!!17Graph displays data accurately and scientific conventions observed:Computer-generated using Google SheetsHas graph number and informative title.Is correct type; labeled with data values.Axes’ labels have quantities & units, with appropriate labels.Axes’ scales are properly spaced.A sample calculation is included.A trend line or curve has been added over data points.15Minor flaws, shortcuts or inconsistencies, poor execution, or omission of one of the above conventions. 12Most data not accurately plotted, and/or graph is misleading or incomprehensible due to major flaws in execution. Wrong type of graph. Missing more than one convention above.CONCLUSION & EVALUATIONSCOREDESCRIPTION20Achieves all of the below requirements but is exceptionally well-written, thorough, and professional. Easy to read and understand the entirety of the lab and its significance.17Question & Hypothesis are restated in 1st paragraph.Findings are accurately retold and summarized, using data from lab in 2nd paragraph.Hypothesis is accepted or rejected, citing evidence.Most relevant limitations or sources of errors identified and discussed in detail in 3rd paragraph.Summary paragraph discussing the final analysis of how your data, research, and experimental design leads to a particular conclusion answering your original research question.Proper “Works Cited” section included in APA format15Some elements executed superficially and/or incompletely. May be missing one of the above required points.12Is a loose collection of facts and details that do not provide a cohesive summary. Is missing more than one of the above requirements.“I confirm that this lab report is completely my own work and that no other student’s work (even in part) was used for this report without being properly cited.”Signature:________________________________________Date:______________________TOTAL POINTS: / 120Student Example of Great Lab ReportThe Effect of Varying Concentrations of Antibacterial Hand Soap on E. coli Growth as Measured by the Zone of Inhibition Research Question: What is the effect of differing concentrations of antibacterial hand soap on bacterial growth of E.coli, as measured by the zone of inhibition?Hypothesis & Data-Based Explanation: “If there is a relationship between differing concentrations of antibacterial hand soap and the zone of inhibition diameters, then the expected results will be the higher the concentration of hand soap, the larger the zone of inhibition will be. That being said, disks coated in a 100% concentration of hand soap will have the largest zones of inhibition. Disks coated in a 50% concentration of hand soap will have smaller zones of inhibition, and disks coated in sterile distilled water will have no zones of inhibition. An antibacterial Dial? Pomegranate and Tangerine hand soap will be used in this experiment. The active ingredient in this hand soap is a compound called benzethonium chloride ( DIAL? ?Antibacterial Hand Soap, 2014). ??According to the NIH, “[benzethonium chloride] is shown to be effective in mediating its antimicrobial action against bacteria, fungi, mold and viruses.” (NIH, March 10, 2018). This supports the stated hypothesis because it suggests that the more of the active ingredient that comes into contact with the paper disks, the less bacterial growth there will be, and thus the zones of inhibition will be much larger. This should compare to the much smaller zones of inhibition that will occur around paper disks that come into little to no contact with the active ingredient (as there will be more bacterial growth). Independent Variable: The differing concentrations of antibacterial hand soap. Dependent Variable: Bacterial growth, which is measured by the zone of inhibition diameter.Variables Table: Variable to ControlExplanation of Possible Effects on ExperimentMethod to Control VariableTemperature of the petri dishIf the petri dishes are exposed to varying temperatures, the amount of bacterial growth they inhibit could become skewed. According to an article entitled; “Temperature range for growth of Escherichia coli Serotype O157:H7 and Selected Coliforms in E. coli Medium,” varying strains of E. coli tended to survive and reproduce best in warmer temperatures, proving these conditions attractive for bacterial growth. ( HYPERLINK "" Raghubeer and Matches, April 1990). That being said, if each petri dish were to be set in completely different temperature conditions, the results of the experiment would not be accurate, because they would not comply with the independent variable that has already been selected (antibacterial hand soap concentration).In order to control this variable, each petri dish will be placed in the same incubator for 48 hours. The petri dishes will not experience disruption from changing light, or passing waves of warmth or coolness. Spacing of the paper disks If the paper disks are not spaced evenly, and the zones of inhibition grow fairly large, they might collide with one another and thus the results of the experiment would be immeasurable and in return the antibacterial properties (or lack thereof) of the hand soap used in this experiment would not be proven. The paper disks will require a few centimeters of spacing from one another. The antibacterial hand soap product used Different products tend to contain different ingredients, which could skew the results of this lab. This is because an unaccounted for ingredient could be the thing to cause change in the zones of inhibition, as opposed to the intended benzethonium chloride. Dial? Pomegranate and Tangerine antibacterial liquid hand soap will be the only hand soap used in this experiment. The concentration of this hand soap will be the independent variable. ?The amount of hand soap applied to each individual paper disk If the amount of hand soap applied to each individual paper disk varies, the zones of inhibition may be drastically different from one another, despite being coated in the same concentration of hand soap. This would not accurately prove the effectiveness of Benzethonium Chloride on killing E. coli bacteria, because measurements of the antibacterial hand soap and zones of inhibition could not be compared to one another.In order to coat each paper disk with roughly the same amount of soap, the process of dipping the paper disks into the soap mixture will be the same. Each disk will sit in the soap mixture for 5 seconds, and then be removed with sterilized tweezers, without being wiped of any excess soap mixture.The strain of bacteria that grows on the petri dishDifferent strains of bacteria grow at different rates, and require different temperatures and conditions in order to thrive. For this reason, if the petri dish has excessive exposure to the outside environment, the results may become skewed, due to many types of bacteria inhabiting the nutrient agar. Certain bacterias may also be more resistant to the antibacterial hand soap that is being used, proving again ineffective lab results.The petri dish will be covered ?as often as possible, in order to limit the insides surface contact with different strains of bacteria (that are not intended to be tested). Amount of nutrient agar in each petri dishThe more available nutrients, the more willing bacteria may be to grow and reproduce. If the amount of nutrient agar drastically differed between the two petri dishes, the results could become skewed and thus proven inaccurate, because more bacteria may grow on one dish, regardless of the independent variable. A teacher will measure out accurate amounts of nutrient agar for each petri dish.Materials List: ?2-Petri dishes with prepared nutrient agar1-100 mL beaker of ethanol1-forceps10- sterilized paper discs.5 mL E. coli suspension broth1 mL sterile distilled water 1-glass stirring rod1-Incubator3- 15 mL disposable plastic cups1-10 mL ?graduated cylinder1 bacteria spreader1-Permanent marker1-metric ruler1-Calculator1 mL Dial? Pomegranate Tangerine antibacterial liquid hand soap Procedures: ?Sterilize all tools in ethanol.Have teacher pour .25 mL of E. coli broth onto each petri dish, and use sterilized bacteria spreader to evenly distribute the broth around the area of the dish. In a graduated cylinder, measure out .5 mL of hand soap. Then pour the hand soap into one 2 oz. plastic container. ?Using the pair of tweezers, dip 4 sterilized disks into the measured hand soap, coating them evenly, for 5 seconds. Still using the tweezers, evenly place the paper disks onto one of the petri dishes, leaving roughly the same amount of space between each. BE SURE to leave room for one more paper disk in the center of the petri dish. When complete this should create a five on a dice shape. Repeat step #3 in a second plastic container. Add .5 mL of sterile distilled water to the plastic container, and mix the soap and water together using the metal stirring rod. Make sure to mix the two slowly and carefully, avoiding an excessive creation of bubbles. Using 4 more paper disks, repeat step #4 and #5 in the 50% Dial soap concentration mixture. Place the paper disks onto the second petri dish with nutrient agar. Add the remaining .5 mL of sterile distilled water to the third plastic container.Dip the remaining two paper disks into the water for 5 seconds, coating them evenly, and then place them in the center of each petri dish. Cover the petri dishes and allow the paper disks to soak for 5 minutes. Using a permanent marker, mark the placing of each paper disk. Place both petri dishes (upside down) into an incubator, and allow them to sit for 48 hours. Once the 48 hours are over, measure the zones of inhibition of each paper disk and record them in a journal. Then, find the average zones of inhibition and record them in a journal. Data Collection:Data Table 1: The Effect of Antibacterial Hand Soap Concentration on Growth of E. coli, as measured by zone of inhibition diameters (mm)Antibacterial Hand Soap Concentration (%)Zone of Inhibition (mm)Average Z of I (mm)0 (Water)0.00.00.0500.050.0450.040.040.051000.20.16250.150.20.1Sample Calculation: ?For Average Zone of Inhibition calculation0.05 + 0.04 + 0.04 + 0.05 = 0.18 ???????????????0.18 / 4 = 0.045Data Processin32385020764500gConclusion:The purpose of this experiment was to see if varying concentrations of antibacterial hand soap would have an effect on the bacterial growth of E.coli. It was hypothesized that there would be an inverse relationship between antibacterial hand soap concentration and bacterial growth. In other words, the higher the concentration of hand soap, the less bacterial growth that would inhabit the petri dishes. 4426585122682000The resulting data from the experiment seems to support the initial hypothesis. The paper disks dipped in sterile distilled water had no zones of inhibition, meaning that the sterile water had no antibacterial properties. The paper disks dipped in a 50% concentration of antibacterial hand soap had small zones of inhibition, measuring to be 0.045 mm wide on average. Finally, the paper disks coated in a 100% concentration of antibacterial hand soap had the largest zones of inhibition, measuring 0.1625 mm wide on average. The larger the zones of inhibition, the more effectively the product worked to kill the E.coli bacteria. However, there were a few potential sources of error that could have affected the results of the lab. ?First, there should have been clearer time limits set for how long the paper disks used were allowed to soak in the hand soap solutions. ?By not being consistent with this variable, it is possible some trials experienced more saturation of the disks than others. Also, there was no accurate method established to ensure the exact amount of solution each paper disk received. ?Some disks could have been coated with more solution and excess liquid could have been wiped off or because the procedure simply called for dipping the disks in the solutions without being more accurate. Another unexpected result was how difficult it would be to make a judgement call on where exactly the zones of inhibition started and ended (see example on right): ?it was not clear whether to measure the widest parts of the Z or I or even where those started and stopped. So this method of measurement required a judgement call which may or may not have involved some amount of personal bias and error.In conclusion, the original research question and hypothesis seems to be supported by the experimental results from the lab. ?The average Zones of Inhibition were overall larger when a higher concentration of hand soap was applied on the paper disks. This seems to validate the idea that higher concentrations of hand soap have higher antibacterial properties. ?This conclusion is also supported by a study done by Abbas SZ, Hussain K, Hussain Z, Ali R and Abbas T that showed “Antibacterial activity of these soaps was different from each other. Increasing concentration (150 mg/mL>100 mg/mL>50 mg/mL) of each showed good result against reference bacterial strain especially against Staphylococcus aureus and Escherichia coli.”(Abbas SZ, Hussain K, Hussain Z, Ali R and Abbas T, 2016).Works Cited:Raghubeer EV, Matches JR. ?(1990, Apr 28). ?Temperature range for growth of Escherichia coli serotype O157:H7 and selected coliforms in E. coli medium. ?Retrieved from? Pomegranate Tangerine Antibacterial Hand Soap with Moisturizer. (n.d.). ?Retrieved from F, Aboulmagd E, and Amin TT. (2014, July). ?Antimicrobial activity of commercial “antibacterial” handwashes and soaps. ?Retrieved from SZ, Hussain K, Hussain Z, Ali R, Abbas T (2016). ?Anti-Bacterial Activity of Different Soaps Available in Local Market of Rawalpindi (Pakistan) against Daily Encountered Bacteria. ?Retrieved from ................
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