Maricopa Community Colleges Microbiology Laboratory Questions
Lab 10Identification of an Unknown Using the Scientific MethodIntroduction: Connecting Your Learning Every science student must understand and be able to apply the steps of the scientific method to their work. While some laboratory assignments in this course are demonstrations, for example, how the microscope works, others are hands-on investigations. Understanding how scientists properly set up experiments and consider the role of chance events in their results will certainly enable a student to apply science to everyday life.This laboratory will utilize what has been learned in previous labs about microscopic, biochemical, and cultural characteristics of microorganisms to develop an identification scheme that could identify an unknown organism. The scientific method will be used in developing this identification scheme.Readings, Resources, and AssignmentsMultimedia ResourcesNoneRequired AssignmentsLab 10 AssignmentFocusing Your LearningCourse CompetenciesIdentify microorganisms in the lab, emphasizing bacteria.Utilize a compound microscope to visualize microbial organisms.As you work through this lab, consider the objectives below.Lab ObjectivesBy the end of this lab, you should be able to:Identify unknown microorganisms using microscopic, culture, and biochemical test results.Utilize the scientific method to develop an identification scheme to identify an unknown organism. Background InformationReview concepts from previous labsIn previous laboratory exercises, organisms were identified based on microscopic, biochemical, and cultural characteristics. In this laboratory exercise, the scientific method will assist in determining an identification scheme of an unknown organism. The scientific method will be used to determine the identification of an unknown organism. The student will also need to draw upon their cumulative knowledge of previous microbiology lab concepts to correctly complete this final lab activity.Before beginning this lab activity, please review the following lab objectives as they were covered in these previous labs. Mastery of these concepts is necessary to successfully complete Lab 10. Students should especially review the Lab 9 content:Lab 4:Identify bacteria using various staining techniques.Describe the differences in types of stains and uses for each stain.Lab 6:Explain biochemical test procedures for the identification of microorganisms.Lab 7:Identify optimum growth conditions for various microorganisms (nutritional, oxygen, and temperature requirements).Identify the use of various media for the culture and identification of microorganisms.Lab 9:Identify organisms under the microscope.Identify organisms using biochemical tests.Identify organisms using culture media.Identify unknown organisms using microscopic, biochemical, and culture growth.The Scientific Method ProcessThe scientific method is a systematic and rational scientific process of investigation used to study and discover the unknown. As with any tool, the scientific method requires practice and rigidity in its use so that it can be effective. The scientific method is a series of steps that one follows when performing an experiment in order to achieve acceptable conclusions for the study undertaken.The scientific method is a series of steps that one follows when performing any experiment in order to achieve acceptable conclusions for the study undertaken. Only by following the accepted scientific method process, as depicted in the steps below, will the results and conclusions of a scientific study be considered valid.Observation: The first step of the scientific method is making a puzzling background observation. By seeing something intriguing or interesting in the environment, by reading literature, or by merely wondering about something (sometimes referred to as armchair science), interest is generated which leads the scientist to ask a specific scientific question This type of question is looking for the explanation behind the original puzzling phenomenon. For example, if Ashanti noticed that her patient had a rash, her scientific question could be "Why does this patient have a rash?"Example Observation: While working in the microbiology lab one might observe that some samples of a certain bacteria grow more readily than others. This would naturally lead to asking the scientific question, “Why do some bacterial cultures grow faster than others?”Hypothesis: The second step of the scientific method is stating the hypothesis. A hypothesis is a possible answer to the scientific question; it provides a possible, testable explanation for the puzzling phenomenon that was observed. In other words, the hypothesis is a simple statement of the expected outcomes and should not be confused with a prediction or an educated guess. It is usually accompanied by a thorough research of the literature, which leads up to the statement of a hypothesis. The hypothesis must be stated in measurable terms that relate directly to the problem.Example Hypothesis: Continuing from the above example question, one would read more about bacterial growth and discover the importance of nutrients in promoting bacterial growth. This could lead to the hypothesis that nutrient treatment X will promote bacterial growth. This hypothesis could be stated in a measurable manner as follows:If nutrient X increases bacterial growth, then adding nutrient X will increase the growth rate of the bacterial culture.ORIf bacterial samples that have had nutrient X added grow at a faster rate, then nutrient X does promote bacterial growth. Experiment: The third step of the scientific method is the experiment, which includes experimental design and the actual experimentation. In any scientific experimental design, two groups of subjects/objects should be used in the experiment. These groups should be designed to be as identical in all possible ways (same size, age, species, health, etc.) as is possible. One of the groups is the control group, which is not exposed to the factor that the scientist wishes to test. This control group functions as a reference group to which a second or experimental group (the group that is tested by being exposed to the hypothesized factor) is compared. In addition to using both a control group and an experimental group, to produce valid scientific results these important factors must also be included in the experimental design.
Random sampling- Subjects of the experiment should be chosen and distributed into test groups randomly.Minimum sample size- There must be at least 30 test subjects distributed between the experimental and control groups of the experiment.Reproducibility- To be valid, all experimental results must be able to be reproduced should another scientist later wish to confirm those results. In order to ensure reproducibility, the experiment's "method" must be so clearly stated that any other researcher in the world could exactly replicate the same experiment and produce statistically similar results. Therefore, it is important that the original experiment be repeated several times before the results are released to the scientific community.Independent variables are the factors that can affect the outcome or results of the experiment. Independent Variables will intentionally be set or changed by the scientist during the experiment. To have a valid experiment note that only one independent variable can be changed at a time between the control group and the experimental group. That way the scientist can be sure that any differences in the results between the control group and the experimental group are due to that one independent variable that was tested. If it was the only factor that was different between the control group and the experimental group, this one independent variable must be the cause of any differences between their results. Example: To study the effect of nutrient X on bacterial growth, the scientist would need to develop a standard set-up that is used for the control group of bacterial cultures. The experimental group of cultures then would be subjected to the exact same control set-up but with the addition of only one additional factor which is nutrient X, the treatment that the scientist wants to see the effects of. Note the scientist would not try adding 3 different nutrients treatments (X, Y, and Z) to the experimental group all at the same time, because if the results differed between the control group’s results and that experimental group’s results there would be no way to know if those differences were caused by nutrient X alone, or by X+Y+Z all together, or by just X+Z, etc.Extraneous variables are other independent variables that are not intended to be tested and therefore should be considered and (as much as possible) held constant between the control group and the experimental group. If these extraneous variables were unintentionally not held constant, then they may have extraneous additional and unplanned impacts on the results. If extraneous variables are not held constant between the control group and the experimental group, then it would not be possible to determine what actually caused the results that were observed between the two groups (the effects of the experiment). It is important to consider any possible extraneous variables when analyzing experimental results. Example: To test the impacts of the nutrient treatment on bacterial growth, the scientist would want to make sure that other independent variables that could impact the results were controlled. The lighting, temperature, and type of growth medium should be the same in all respects except the addition of the nutrient treatment to the experimental group. If after the experiment it was found that the control group was actually in a draftier part of the lab that tends to be a bit cooler, then that would be an extraneous variable that could have unexpectedly impacted the results.The Dependent variable is the results variable. Its results are caused by the combination of independent variables that the test subjects were exposed to in the manipulated experiment. The dependent variable is the one that is measured as the effect or actual results of the experiment.Example: Continuing with the above example experiment, the dependent variable that the scientist would measure to “see” the results is the bacterial growth rate. To see if there was an impact of the added nutrient X, the scientist would measure the average growth rate of the control group samples and compare it to the average growth rate of the experimental group’s samples. The scientist must compare the results between the experimental group and the control group to see if they were the same (meaning no effect of the treatment) or different (which would indicate some effect).Conclusion: It is important to understand that the whole point of the entire experiment process is to test if the hypothesis was in fact the correct explanation for the initial puzzling phenomena. So, the final step of the scientific method process is to compare the results of the experimental group to those of the control group in order to conclude whether the original hypothesis has been supported by the actual results that were observed, or if the hypothesis needs to be rejected based upon the collected data. To make the conclusion, the hypothesis must be overtly evaluated based on the actual results of the experiment. Then the researchers should explain the observed relationships between the independent variable that was tested and the dependent variable of the experiment. The conclusions are then used to accept or reject the hypotheses.Example Conclusion: Based off the results from the experiments, the growth rate of the experimental group did not significantly differ from that of the control group. The results do not support the hypothesis. Since the addition of nutrient X does not seem to increase the growth rate of this bacteria, the conclusion would be to reject the hypothesis.Using the scientific method, laboratory experiments can be designed and performed while keeping in mind the equipment and safety issues in the lab.Throughout the lab work in this course, students have learned to identify organisms based on their microscopic, biochemical, and culture characteristics. Using this knowledge, the student should now be able to design an experiment according to the scientific method process to identify a causative pathogenic organism when given an example scenario.Assessing Your LearningWarning: You are expected to submit your own, individual work. Using work completed by anyone other than yourself is plagiarism. This includes resources found on Internet sites. Posting assessments on an unauthorized website, soliciting assessment answers or the acquisition of assessments, assessment answers, and other academic material is cheating. Cheating and/or plagiarism will result in a failing grade for the course.AssignmentsSubmit LAB 10(opens in a new tab).Important information:Copy and paste the list of Laboratory Exercise Questions into a Word document. Compose answers to these questions in the Word document and save the file as a backup copy in the event that a technical problem is encountered while attempting to submit the assignment. Make sure to run a spell check.You will be submitting your answers to the lab assignment in two parts. The first part of the lab assignment consists of the laboratory exercise questions. The second part of the lab assignment is the application question. The first textbox on the submission page corresponds to the first part of the lab. Be sure to paste the laboratory exercise questions, with your answers, into this textbox. The second textbox on the submission page will be for your response to the application question. NOTE: This lab assignment has questions related to binomial nomenclature. Please note that the assessment system does not accept formatted text, so you will need to indicate any italicized words by adding “IT” in parentheses after each word that is to be written in italics, (IT). For example, the common fruit fly is genus Drosphila and species melanogaster. When written, it is Drosophila melanogaster. From this example, the correct way to represent the italicized words is by typing, Drosphila (IT) melanogaster (IT).Laboratory Excercise Questions~~1. The following scenario will provide information that you will need in order to use the scientific method to determine how you would be able to identify an organism.The scenario is: A patient is admitted to the hospital with the following symptoms: sudden high fever, stiff neck, severe headache, nausea, altered mental status, sensitivity to light.These symptoms correspond to bacterial meningitis. In order to choose a correct course of treatment, it must be determined whether the patient has an infection with Neisseria meningitidis or Haemophilus influenzae.Using the scientific method, address the following: What is the background observation? What is the scientific question that comes from that observation? [Describe the problem/scenario and list the scientific question it leads you to ask.] (2 points)Which organism do you propose caused the problem? What is your hypothesis? (1 point)Describe the predicted cultural and biochemical results that correspond to the hypothesized organism as compared to the alternative possible causative organism. (6 points)Which experiments are required to test your hypothesis? Describe how you would conduct a well-designed scientific experiment using the necessary stains and biochemical test(s). Recall that good experiments include the use of control and experimental groups, random sampling, appropriate sample size, and a reproducible methodology. (8 points)What specific actual results should you see if your hypothesized organism is truly the causative organism? (6 points)Given the above results, what would your conclusion be? (1 point)Application Question~~2. How might the information gained from this lab pertaining to identifying unknown bacteria by using the scientific method process be useful to you as a healthcare professional? (6 points)Key components of critical thinking and application include the following:Demonstrates comprehension of the scientific principles. (40%)Displays competence in applying scientific knowledge to your professional life. Relevant content is supported by facts, data, and detailed examples. (40%)The application paragraph is organized and structured. (10%)Use of accurate scientific terminology. (10%)Critical Thinking and Application of Information0%1-59%60-89%90-100%Is your application a detailed description of how the lab content is relevant to your life?Application did not adequately demonstrate application or comprehension of the scientific principles. Did not include detailed examples, facts or data. Or the application was not included.A few areas of the application demonstrated some application and comprehension of the scientific principles by applying the knowledge to the student’s personal and professional life, but lacked detailed examples to support the content provided. Application demonstrated some organization and structure within the paragraph.Most areas of the application demonstrated evidence of critical thinking and comprehension of the scientific principles. Displayed good competence and the relevant content was supported with good use of examples that apply the concepts and describe how the information will be relevant and useful to the student’s personal or professional life. The application paragraph is primarily presented in an organized and structured manner.Application included a complete and detailed description of how the concepts are relevant and useful or applicable to the student’s personal or professional life. The application includes detailed examples and reveals insight into the scientific principles. The application paragraph maintains a strong sense of purpose and organization throughout.