Mystery Foods Macromolecule Lab
Honors Biology
Name _______________________________________________ Period __________ Date _________________
You are the scientist in a lab at the National Institute of Health, where you are
studying the American diet and its affects on the health of the population. You have
been assigned the task of analyzing 10 unknown foods to determine what organic
macromolecules they contain. Since you cannot see the structural or chemical
formulas by looking at the foods, you must use chemical indicators and other tests to
determine the content of each sample.
After completing the tests, you will have analysis questions to complete using your new
knowledge of testing for macromolecules in food.
Chemical Indicators – Use the PowerPoint displayed in class to fill in
the following chart.
Test
Performed
Lipid test
Starch test
Sugar test
Protein test
Indicator used
Negative result
Positive result
Chemical Indicators and Foods Tested
Use (-) and (+) (++) (+++) for results
Sample
Water
1
2
3
4
5
6
7
8
9
10
Name of
Food
Iodine
(Starch)
Benedicts
(Sugar)
Paper
smear
(Lipids)
Biuret
(Protein)
Lab Analysis
1. You have been given an unknown solution in a hospital. A diabetic patient
has consumed a liquid and is not sure if it contains any sugar. What two tests
would you perform to determine if the unknown liquid contained any
monosaccharide, disaccharide, or polysaccharides?
Use your knowledge of carbohydrates and subunits to select the lab tests.
Explain how both tests are performed and what the results would be if the
solutions contained any of the sugars listed above. Remember that the patient’s
life may be in your hands. GOOD LUCK!
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2. You have tested an unknown sample with Biuret reagent and the test was
positive. Then, the solution was placed on paper and allowed to dry. When
the paper was held up to the light, it was translucent. The solution boiled
with Benedict’s reagent and did not change color and neither did the iodine
when applied.
a. What two macromolecules does this sample contain? Give reasons for
your answer
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b. What type of food could the sample be? List 3 examples of foods that
the sample could be.
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3. A vegan wants to know which of the foods you tested in the lab contained
protein, but did not come from an animal. Were there any food samples that
a vegan would be able to eat as a source of protein? Which of the proteins
that were tested today would a vegan not eat?
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4. What is the purpose of testing water at each station? If there was a positive
test for a macromolecule in the water, what do you think the reason could
be? Explain you answer.
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5. Which of the foods tested contained lipids? What should people understand
about saturated and unsaturated fats in the diet? Indicate which tested foods
were saturated and how we know.
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