weigh evidence and make decisions based on strengths and limitations of scientific knowledge and the scientific method

  • recognize and explain how the scientific method is used to solve problems
  • make observations and discriminate between scientific and pseudoscientific explanations
  • weigh evidence and make decisions based on strengths and limitations of scientific knowledge and the scientific method
  • use knowledge of biological principles, the scientific method, and  appropriate technologies to ask relevant questions, develop hypotheses,  design and conduct experiments, interpret results, and draw conclusions

This is the culminating lab assessment in BIOL 103. It is designed to  assess your ability to apply the principles of the scientific method.

The Effect of low pH on Enzyme Activity

Design an experiment in which you will test the effect of an acidic  fluid on enzymatic activity. Recall: enzymes are proteins! To complete  this project, it may be useful for you to first review the Scientific  Method Tutorial, information about pH and enzymes in the text book and  course modules, Lab 1 (Introduction to Science) and Lab 4 (Enzymes).  As  you review Lab 4, you will be reminded that there are several factors  that impact enzymatic activity: pH, temperature, and amount of  reagent. It is OK to use the same enzyme/substrate/method as you did in  lab 4 (but modify the treatment), or you can search on-line to find a  different enzyme/substrate/method for measuring enzyme activity for your  project (include all references).

As you design your experiment for this project, please remember that you are trying to examine how an acidic fluid  will modify the outcome of an enzymatic reaction.  To successfully  complete this project, you will need to identify the question(s) being  asked in your experiment and the hypothesis that you are testing.  In  your experimental design, you must clearly explain what you are doing.  That means that you will need to identify the enzyme, the substrate, the  acidic fluid used as treatment, the control treatment and the method of  measuring enzyme activity, as well as explain your experimental  protocol.  You must also thoroughly explain how the acidic fluid  impacted enzyme activity based on the results from your own experiment  as well as knowledge of enzymes and pH from the text book, modules, lab  manual and potentially additional information sources.

Hint: Keep in mind that the acid will change the  environmental conditions of the experiment (for example, a low pH value  could change the shape of the active site on the enzyme protein),  without directly participating in the reaction.

Lab Materials 

You may need all or some of the following, depending on your experimental design:

Materials from your lab kit:

  • pH paper
  • hydrogen peroxide solution (you can purchase this at a pharmacy if you have used up the bottle that came with the lab kit)
  • plastic beakers or cups
  • vinegar
  • yeast (can be purchased at grocery store if more is needed)
  • balloons
  • plastic bottle
  • marker for labeling of beakers
  • Cell phone/digital camera – pictures required

You may choose to use additional materials (different acidic fluids  and/or different organisms and/or different substrate if you chose an  enzyme other than catalase).


Include the following in your outline:

  • Name of enzyme you will use
  • Name of organism (if applicable)
  • The substrate and products in the chemical reaction
  • Method for measuring enzyme activity
  • Treatment: acidic fluid(s), pH, length of exposure, how you will treat your samples
  • The control(s) in the experiment
  • Hypothesis
  • How you will present your data (table and/or type of graph)
  • Anything else you would like to get feedback on before you start your experiment

Write a lab report that includes the following: 

1. Title page: descriptive title, your name, course name, semester

2. Introduction: general background information about enzymes and  specific information about your chosen enzyme, the question(s) that you  are asking and a clear hypothesis for your experiment (20 points).

3. Design an experiment. Provide a detailed description of the  materials and methods used to conduct the experiment. Identify control  and experimental samples, as well as independent and dependent  variables. Also include the methods used for data collection and  analysis (20 points).

4. Conduct the experiment and record your results. Take picture(s) of  your results. What did you observe? Present your data in table and/or  graph format. Remember to label everything and include the unit of  measure with all numbers (20 points)

5. Use your knowledge of enzymes and pH to interpret and discuss your  results. It may be necessary for you to refer to the OLI course  modules, lab manual and/or use additional information resources. What  effect does the acidic treatment have on enzyme activity? Did you get  the expected results? Explain. (20 points)

6. State a specific and accurate conclusion. Is your hypothesis  supported by the results? Looking back, how could you have improved your  experiment? (10 points)

7. Include a list of references to all information sources used in APA format (5 points).

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