Name:____________________________ Date:_____________________ Hr.:_____
Macromolecules Lab
Introduction:
All living organisms are composed of various types of organic molecules, such as carbohydrates (starches and
sugars), proteins, lipids, and nucleic acids. These substances, contained in the foods we eat, provide us with the
energy and cellular building blocks necessary for life (you really are what you eat!) These molecules are taken
into our cells and are broken apart to provide the building blocks cells need to carry out functions like growth and reproduction.
These macromolecules are similar in that they all contain the elements of carbon, oxygen, and hydrogen. These elements occur
in different ratios and are arranged in different structures in each class of these macromolecules, which accounts for their
different properties. Several of these molecules can be detected by simple chemical tests. In this lab, you will test for specific
compounds and then determine if those compounds are present in plant-based foods.
Objective:
To determine the organic compounds present in plants and know the procedure to test for each type of compound
Materials
beaker, graduated cylinder, test tubes, test tube clamp, Benedict's solution, Biuret solution, Sudan III solution, Lugol's iodine
solution, prepared food items
Hypothesis: What test(s) do you think will show a
positive result for each type of food? Fill in the chart.
Food
Prediction
Protein
Lipids
Carbs
Potato
Onion
Almond
Tofu
Apple
Soymilk
Procedure: Part I -Testing of Known
Substances
Protein test:
1. Place 5 mL of the gelatin solution into your test
tube.
2. Add ten drops of Biuret solution.
3. Observe any color change
Glucose (sugar) test:
1. Place 5 mL of the glucose solution into your test
tube.
2. Add 3 mL of Benedict's solution.
3. Place the tube in a beaker of boiling water and boil
for five minutes
4. Use test tube clamps to hold hot test tubes
5. Observe any color change
Oatmeal
Starch test:
1. Place 5 mL of the starch solution into your test
tube.
2. Add 5 drops of Lugol's iodine solution.
3. Observe any color change
Lipid test:
1. Place 5 mL of vegetable oil into your test tube.
2. Add 5 drops of Sudan solution and shake gently
3. Observe any color changes
7th Grade Science- The Living Earth- Cell Energetics (Classwork)
Name:____________________________ Date:_____________________ Hr.:_____
Food Substance
Test
Results
Gelatin
Biuret solution
Glucose
Benedict's solution
Starch
Lugol's iodine
solution
Sudan III reagent
Lipid
Procedure: Part II - Testing of UnKnown Substances
Using the same procedures as in Part I. Predict and Test each of the Unknown substances for each molecule.
Food
Tests Results
Protein
Lipids
Questions:
Carbs
1. What happens to lugol’s solution when it comes into
contact with starch? Benedict’s with sugar? Sudan’s
with lipids? Biuret’s with protein?
Potato
Onion
Almond
Tofu
2. What tests would you suspect would show a positive
result with baked beans?
Apple
Soymilk
Oatmeal
3. What is the 4th type of macromolecule that we didn’t test for today?
4. What do our bodies receive from breaking down these organic molecules?
5. Predict which macromolecules should be present in the following food substances and indicate which test you
would apply in order to detect the presence of that macromolecule. You may need to consult additional resources.
Food Substance
Predicted
Macromolecule
Test to be used
Orange Juice
Craker
Egg White
Honey
7th Grade Science- The Living Earth- Cell Energetics (Classwork)