Biology Lab Assignment: The Chemistry of Life
Pre-Lab Questions
1. Nitrogen fixation is a natural process by which inert or unreactive forms of nitrogen are transformed into usable nitrogen. Why is this process important to life?
2. Given what you have learned about the hydrogen bonding shared between nucleic acids in DNA, which pair is more stable under increasing heat: adenine and thymine, or cytosine and guanine? Explain why.
3. Which of the following is not an organic molecule; Methane (CH4), Fructose(C6H12O6), Rosane (C20H36), or Ammonia (NH3)? How do you know?
Experiment 1: Testing for Proteins
Data Tables and Post-Lab Assessment
Table 1: A Priori Predictions
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Sample
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Initial Color
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Final Color
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Is Protein Present?
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1. Albumin Solution
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2. Gelatin Solution
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3. Glucose
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4. Water
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5. Unknown
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Table 2: Testing for Proteins Results
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Sample
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Initial Color
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Final Color
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Is Protein Present?
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1. Albumin Solution
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2. Gelatin Solution
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3. Glucose
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4. Water
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5. Unknown
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Take a picture of your results. Include a note with your name and date on an index card in the picture. Insert picture here:
Post-Lab Questions
1. Write a statement to explain the molecular composition of the unknown solution based on the results obtained during testing with each reagent.
2. How did your a priori predictions from Table 1 compare to your actual results in Table 2? If there were any inconsistencies, explain why this occurred.
3. Identify the positive and negative controls used in this experiment. Explain how each of these controls are used, and why they are necessary to validate the experimental results.
4. Identify two regions which proteins are vital components in the human body. Why are they important to these regions?
5. Diet and nutrition are closely linked to the study of biomolecules. Describe one method by which you could monitor your food intake to ensure the cells in your body have the materials necessary to function.
Experiment 2: Testing for Reducing Sugars
Data Tables and Post-Lab Assessment
Table 3: Testing for Reducing Sugars Results
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Sample
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Initial Color
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Final Color
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Reducing Sugar Present
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1 - Potato
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2 - Onion
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3 - Glucose Solution
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4 - Water
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5 - Unknown
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Take a picture of your results. Include a note with your name and date on an index card in the picture. Insert picture here:
Post-Lab Questions
1. What can you conclude about the molecular make-up of potatoes and onions based on the two tests you performed? Why might these foods contain these substance(s)?
2. What results would you expect if you tested ribose, a monosaccharide, with Benedict's solution? Biuret solution?
Experiment 3: What Household Substances are Acidic or Basic?
Data Tables and Post-Lab Assessment
Table 4: pH Values of Common Household Substances
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Substance
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pH Prediction
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Test Strip Color and pH
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Acetic Acid (Vinegar)
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Sodium Bicarbonate Solution (Baking Soda)
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Take a picture of your results. Include a note with your name and date on an index card in the picture. Insert picture here:
Post-Lab Questions
1. What is the purpose of determining the pH of the acetic acid and the sodium bicarbonate solution before testing the other household substances?
2. Compare and contrast acids and bases in terms of their H+ ion and OH- ion concentrations.
3. Name two acids and two bases you often use.