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Tai

Identifying Organic Molecules Lab - Questions

1. If you were given an unknown food sample and asked to identify its contents, which testwould you use to determine the presence of each of these biomolecules?a. Lipids: Brown paper bag testb. Protein: Biuret Reagent testc. Glucose: Benedict Reagent testd. Starch: Iodine Solution test

2. You tested your unknown solution for the macromolecules mentioned above and yourecorded the following observations. A (+) indicated a color change was observed, a (-) indicatesno change in color. What could conclusions could you make about the different macromoleculesthat compose the unknown solution?

The unknown solution contains lipid, and protein. But does not contain Glucose or Starch. Theunknown solution is mostly some kinds of food (most likely protein full meat) fried or cooked withoil (lipid).

Positive Control Negative Control Unknown Solution

Lipid Test (+) (-) (+)

Protein Test (+) (+) (+)

Glucose Test (-) (-) (-)

Starch Test (+) (-) (-)

3. Jonathan and Molly performed a similar experiment except that in their lab they also tested aslurry made from a McDonalds Happy cheeseburger meal (cheeseburger, fries & a coke) . Whatorganic molecules would you expect to find in the slurry? What portion of the meal may haveprovided each of these?

The biomolecules expected are: Starch (from the fries and buns of the burger), Protein (from themeat of the cheeseburger), Lipids (from the old used to fry the fries and cooking the meat on theburger), and Glucose (from the sweet coke).

4. Thinking back on the work that you did in the lab to identify organic molecules, can you identifyportions of the experiment that you felt were weaker than others? What types of errors could

have been made?

There were systematic errors that could have been made during the experiment. Since thefollowing the procedure was done by two people, there could have been mistakes (filling indifferent amounts of solutions by accident). Also the scientific equipment used was not veryaccurate, this could have altered the results. To improve this experiment, more accurateequipment should be used. Furthermore, one person (or better yet a systematic robot) shouldcomplete the leg work of the experiment for maximum accuracy. Other than that, there shouldntbe anymore notable errors.

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5. Were there any results that surprised you? Explain.

There werent really any test results that jumped at me. I guess I was a tad bit surprised that therewas sugar in potato, and protein in milk. I have always thought of potatoes as an example of afood that isnt sweat, so that was slightly surprising. All my life, I thought of protein as meat; neveras a drinkable substance, so finding protein in milk surprised me a little bit. Other than that, thetest results are mostly as expected.

Results:

Sugar TestSolution: Evidence Of ChangeMilk No changeHoney ChangeEgg White No change

Apple Juice ChangePotato ChangeCorn oil No changeLiver No changeDeionized Water (Negative Control) No changeGlucose (Positive Control) Change

Figure 1: Sugar Test Image

Lipid TestSolution: Evidence Of ChangeMilk No changeHoney No changeEgg White No change

Apple Juice No Change

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Potato No ChangeCorn oil ChangeLiver ChangeOil Solution (Positive Control) Change

Figure 2: Lipid Test Image

Starch Test:Solution: Evidence Of ChangeMilk No changeHoney No changeEgg White No change

Apple Juice No changePotato ChangeCorn oil No changeLiver No changeDeionized Water (Negative Control) No changeStarch Solution (Positive Control) Change

Figure 3: Starch Test Image

Protein Test:

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