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UMUC Biology 102/103
Lab2:The Chemistry of Life
INSTRUCTIONS:
·
On your own and without assistance, complete
thisLab
2AnswerSheet electronically
and submit it via theAssignments
Folder by the date listedintheCourse Schedule (underSyllabus).
·
To conduct your laboratory exercises, use the
Laboratory Manuallocated under Course Content.
Read the introduction and the directions for each exercise/experiment carefully
before completing the exercises/experiments and answering the questions.
·
Save your Lab2AnswerSheet in the following format: LastName_Lab2 (e.g., Smith_Lab2).
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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
Sample
Initial Color
Final Color
Is Protein Present?
1. Albumin Solution
2. Gelatin Solution
3. Glucose
4. Water
5. Unknown
Sample
Initial Color
Final Color
Is Protein Present?
1. Albumin Solution
2. Gelatin Solution
3. Glucose
4. Water
5. Unknown
Table 2: Testing for
Proteins Results
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
Sample
Initial Color
Final Color
Reducing Sugar
Present
1 – Potato
2 – Onion
3 – Glucose Solution
4 – Water
5 – Unknown
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
Substance
pH Prediction
Test Strip Color
and pH
Acetic Acid (Vinegar)
Sodium Bicarbonate Solution (Baking Soda)
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.
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