Biology Osmosis experiment

Biology Osmosis experiment

Need to write a lab report for Osmosis experiment according to the guidelines in the attached document. You must include the data from your experiment as well as results for all four % concentrations of sugar.

Lab Report Format

General Instructions for Writing Lab Reports

Writing a lab report is a standard feature of science lab classes. Writing an organized lab report will help you understand the scientific method.   A person should be able to read your lab report and:

• know exactly how to do this experiment
• find a table, graph or photo of your results
• know what you concluded at the end of your experiment
• know what experiment you would do next to follow up on these results

Science writing is somewhat different from writing for other disciplines. What are the major differences that you should look out for?

• The passive voice is used. So instead of writing, “I measured the bone with the meter stick,” it would be “The bone was measured with a meter stick”. The report is about the work, not about you.
• Keep the language simple and use your own words
• Avoid the pronouns “I”, “We” and “They”
• Write in the past tense for most of the report
• Use the present tense when you draw conclusions and discuss implications
• Methods and Results should be written in the past tense because these are things that have already happened.
• Sentences should be as short as possible, and only the most relevant information is included.
• Direct quotes are never used.
• Everything must be rewritten in your own words. Directly copying (or only slightly modifying) someone else’s work (including the work of other students) is plagiarism and will result in a grade of 0.

The format of a lab report is also different.  These are the seven headings that you will use to write the lab report:

Purpose of this lab: What do you want to learn from this lab? What did you expect the experiment to teach you about biology? This section should consist of only one or two sentences and a hypothesis that predicts the effect of an independent variable on a dependent variable.

Introduction: This part gives background information about the particular subject that the lab covers and the experiment being performed. You will need references for this section. Your references may NOT include the lab manual.

Materials: The equipment and supplies used should be listed. Specific information should be given as to amounts, concentrations, and so on. Make sure you include ALL of the materials used in the procedure outlined in your lab report. Likewise, make sure you include ONLY the materials used in the procedure outlined in your lab report.

Methods: The write-up of the methods should be similar to a detailed recipe. It should be written in paragraph form. A person who has never done this lab should be able to read this section and know exactly what equipment and supplies are needed and how to perform the experiment.   You may wish to include a photograph or diagram of the experimental set-up.

Results: What was the final outcome of the lab? This section will include measurements, illustrations, organized tables and graphs.   A person who has never done this lab should be able to read this section and know exactly what happened in the lab.

• Tables should be given a number and title
• Graphs (or figures) should be given a number and title. Number them independently of the tables.
• Refer to graphs and tables using the number. For example, Table 1 shows …

Analysis and Discussion: This section should explain what the results mean and provide details of any calculations that were used to understand the results.

• Show an example of each calculation. Include units when appropriate.
• Describe what you learned from your results. How does the experiment relate to similar situations? Draw conclusions based on your results that refer back to your original hypothesis.  Indicate whether your original hypothesis was supported or refuted. Refer directly to the Tables and Graphs.
• Incorporate answers to the analysis questions in your lab manual that relate to your results.
• Account for any discrepancies in the data if there are any.
• Indicate how your findings relate to similar situations or what your findings suggest regarding future events. Describe the next experiment that could be done based on the results seen here.

References: When you mention someone else’s work, you give them credit for it. References usually are found in the Introduction and the Discussion section of a report. First, you rewrite it in your own words (Do not use direct quotes!). Then you insert a citation telling where the information comes from. The full information about the reference comes at the end of the report.

For example, in one reference you find the sentence “The Metric System was developed in France under Napoleon in the 1790’s for the purpose of standardization of units as trade expanded through Europe.” You might rewrite this as: The metric system was implemented as a way to standardize units of measurement throughout Europe. It was created in France during the 1790’s (Hoobler et al, 2007).

Assembling Your Report

• Use the grading rubric as a cover page. Be sure the complete names of all group members and your class section are on the cover page.
• Type the report.
• Fasten all parts of the printed report together in order with a paper clip. Do not put the report in a folder.
• Number the pages of the report

Teamwork Self-Evaluation Form

Name:________________________________________________________

Lab Used for Group Project:_______________________________________

Lab Day and Time:______________________________________________

Self-Evaluation:  Please answer these questions about how you personally contributed to the team.

1. On a scale of 1 to 5 (5 = amazing contributor, 1 = did absolutely nothing), how would you rate your overall contribution to the team?_______________________

2. What role did you play in team meetings or discussions (online or face-to-face)? What ideas or work did you contribute?

3. How would you describe the quality of the work you personally were responsible for? How did it compare to work produced by other students?

4. How did you discuss other team members’ ideas for the project? In what ways did you encourage participation by all team members?

6. Give an example of a conflict (a difference of opinion or a problem) within your team and what you did to help resolve it.
7. Did you behave in a professional manner? Were you on time to all classes and team meetings?  Did you follow through on all your commitments?

Individual Team Member Evaluation

Name:________________________________________________________

Lab Report Title:_______________________________________

Lab Section:______________________________________________

List the names of you team members.  Indicate whether or not you would want to work with them again and explain your decision. Be specific.

Team member’s name: ______________________________________yes/no

Explanation:

Team member’s name: ______________________________________yes/no

Explanation:

Team member’s name: ______________________________________yes/no

Explanation:

Grading Rubric for Lab Report 1 – Osmosis

The grading rubric shows you exactly how your professor will grade your report.  The maximum possible number of points that you can earn is broken down by section.  As you are writing your report, you should be using the grading rubric to self-evaluate and ensure that you have included everything that should be in the report.  That is the way to get the highest grade possible.

Names: ______________________________________________________________________

Points earned    Points possible  Criteria Self-Evaluation Questions

1              Purpose               Were objectives of the lab explained in one or two sentences?

Was a hypothesis that predicts the effects of the independent variable on the dependent variable stated?

2              Introduction       Were sentences used to explain the relationship of the following terms: osmosis, osmotic pressure, solute concentration, and solutions (isotonic, hypotonic and hypertonic)?

Were controlled, dependent, and independent variables for this experiment identified?

1              Materials             Was a bulleted list of all equipment and supplies used in this lab provided?

1              Methods             Was the procedure correctly described, written in past tense and passive voice?

5              Results Were the tables completed?

Was a graph showing the results correctly prepared?

Were all tables, figures, and graphs given numbers and titles?

Were the results described?

6              Analysis and Discussion                 Were sample calculations provided?

Were conclusions formulated that explained the results and referred to the original hypothesis?

Were answers to analysis questions in the lab incorporated in this section?

Was there an explanation of any discrepancies noted in the results (if applicable)?

Were findings related to similar situations?

Did you describe an experiment that could be done in the future based on the results of this experiment?

1

References         Did you cite references indicating where information used to complete this report came from?

 

1              Teamwork          Did you complete a self-analysis and evaluate each of your teammates?

Did you work as a team to conduct the experiment, analyze the data, and communicate your findings?

2

Communication                Did you use the style and format appropriate for scientific reports?

Was your report free of spelling and grammar errors?

Sample Lab Report

Name: John Smith

Lab: Lab #9, Enzymes, Effects of pH on Enzyme Activity

Due date:

Purpose

The purpose of this experiment was to study the effects of pH on catalase enzyme activity. If catalase activity is measured by bubbles at different pH values, it is expected that a neutral pH will have more bubbles.

Introduction

Every chemical reaction within the cell requires an enzyme to lower its activation energy.  Even exergonic reactions happen too slowly to be useful without a catalyst.  Almost all enzymes are proteins.  To catalyze a reaction, the enzyme must interact with the reactant or reactants.  This interaction takes place in a region of the enzyme called the active site.  The reactant, or substrate for the enzyme, must fit perfectly into the active site of the enzyme in order for the enzyme to operate.  Therefore, most enzymes are only able to catalyze a single chemical reaction.  This is called specificity, and most enzymes are very specific (Cecamgmmacz, 2011). Under favorable conditions, the enzyme can operate with maximum efficiency, and the chemical reaction occurs very rapidly.  This is an enzyme’s optimum activity (Brooker, 2011).  Some environmental conditions, e.g. temperature and pH, can affect an enzymes activity.  The concentration of enzyme or substrate can also have a dramatic effect on enzyme activity, and that is the variable studied in this report.

The enzyme being studied was called catalase, which was isolated from potato and liver.  Its substrate is hydrogen peroxide, and its products are oxygen gas and water.  In this experiment the behavior of the catalase enzyme was tested at a variety of different pH levels.  A neutral pH of 7 was used as the control environment because the enzyme would react favorably in this environment, since most living organisms (including potatoes) maintain a relatively neutral internal environment.

Materials

• Catalase isolated from potatoes
• Hydrogen peroxide
• Water
• HCl
• NaOH
• Wax pencil
• Metric ruler
• Test tubes
• Pipettes

Methods

Test tubes 1-3 were numbered and labeled at 1cm, 3cm, and 7cm from the bottom of the tube.  Each was filled to the 1cm mark with potato juice (catalase).  Tube 1 was filled to the 3cm mark with HCl, tube 2 was filled to the 3cm mark with distilled water, and tube 3 was filled to the 3cm mark with NaOH.  Each tube was then allowed to sit for 5 minutes at room temperature.  Then, one at a time, each tube was filled to the 7 cm mark with hydrogen peroxide and, after 20 seconds had elapsed, the bubble column height was measured and recorded.  Tube 2 overflowed, so the height of the tube was recorded as the bubble column height for that sample.

Results

The greatest enzyme activity was seen at pH 7, which had 120cm of oxygen bubbles.  At pH 4, 0 cm of oxygen bubbles were measured and at pH 12, 0 cm of oxygen bubbles were measured.

Discussion

Graph 1 shows that only one tube, the tube at pH 7, had a measurable amount of oxygen bubbles, showing that the enzyme was active.  The findings support the original hypothesis that there will be more bubbles at a neutral pH. Normal physiological pH is 7.4, so this tube was very close to the normal pH of living cells.  The enzyme catalase was able to work well under these conditions.  At pH 4 and pH 12, the enzyme was not active.  These extreme pH levels denatured the catalase, changing its shape so that it could not break down the hydrogen peroxide (Brooker, 2011).

This experiment could have been improved by making it possible to measure smaller changes in pH.  This would have allowed comparisons of pH values close to 7, such as 7.8 or 7.3.  Under these conditions, it would have been possible to determine exactly which pH change inactivates the enzyme.

Future experiments could include the one described above.  Another similar experiment could test other important enzymes such as proteases or lipases under different pH conditions.  Another could test the enzymes found in the stomach, which are normally active at acidic pH values.  The results seen here would predict that these enzymes would not be inactivated by acidity, but instead might be inactive at neutral pH.

References

Brooker, Robert, Eric Widmaier, Linda Graham, and Peter Stiling. (2011).   An Introduction to Energy, Enzymes, and Metabolism. Biology 2nd Edition, 118-135.

Cecamgmmacz. (14 July 2011). Enzymes activation energy [Video file].  Retrieved 2 February from http://www.youtube.com/watch?v=Dd1yi2aVoOc