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Name: Date:
Biological Compounds Virtual Lab Report
Background:
Residents in a small rural community notice a strange smell coming from a nearby lake. Scientists are brought in.
How can they identify compounds in the water? Are the compounds organic, and if so, what are they? Scientists
use various chemical indicators to test for organic compounds. In this lab, you are the scientist testing for the
unknown.
Purpose:
Understand that various tests can be used to detect the presence of certain macromolecules. Experiment with
various chemical indicators to identify the presence or absence of macromolecules. Gather and analyze data.
Goal:
You will be performing this experiment in five phases. You will test for starch, protein, and lipid. Then you will
determine the chemical nature of an unknown solution. Then you will test the chemical nature of milk.
Pre-lab questions 1-5 (complete on 10/26):
1. Based on what you know about the following food items, predict what
MACROMOLECULES would be present in each (carbohydrates, proteins, lipids, nucleic
acids). Explain why!
PizzaBreadPeanut
butterEggs-

2. What is a chemical indicator? (Lesson 2.08 Slide 1)
3. Fill in the hypotheses below using these words: (Lesson 2.08 Slide 2)
Sudan III copper sulfate iodine sodium hydroxide black purple red
a. If starch is present, then adding __________ will turn the solution __________.
b. If protein is present, then adding _______________ and _____________ will turn the
solution _________.
c. If lipids are present, adding __________ will turn the solution a BRIGHT _______.
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4. If we are testing the liquids for a color change based on the presence of
macromolecules, what would the control group be? (Circle one).
water with starch added water with lipids added plain water
5. What is the independent variable in the experiment? (Circle one)
Color change absence or presence of macromolecules
6. What is the dependent variable in the experiment? (circle one)
Color change absence or presence of macromolecules
Directions for Lab (complete on 10/27):
1. Under Unit 2 in the course, click on the lesson “2.08 Laboratory: Investigating Biological compounds 1”.
2. Read slides 1-2 carefully (you will NOT need the student guide for this lab!).
3. You can click here to get to the lab : http://tinyurl.com/agorabiologybiocompoundlab
4. Click on “Begin the Lab”
5. Choose a color for gloves
6. Click Start
7. Follow the steps below carefully and answer the questions as you go.
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Phase 1: Test for Starch
1. Click on the pipette labeled “water”.
2. Click on the beaker labeled “H20” to pick up some water.
3. Click above the first test tube labeled “Starch Control (water)” to empty the water into the
tube.
4. Click on the container labeled “starch”.
5. Click above the second test tube labeled “Test for Starch” to empty the starch into the tube.
6. Iodine is an indicator which tests for starch. We will now use iodine to test for the presence
of starch in both the water and the starch tubes. If starch is present, then adding iodine
will turn the solution blue/purple. Place an eyedropper full of iodine into the test tube
labeled “Starch Control (water)” and “Test for Starch”.
7. Use a different stirring rod for each test tube to mix the solution.
8. Record your answers in the chart below.
STARCH: Color Why?? EXPLAIN!
What color did the “Starch
Control (water)” turn?
What color did the “Test for
Starch” turn?
Phase 2: Test for Protein
1. Click on the pipette labeled “water”.
2. Click on the beaker labeled “H20” to pick up some water.
3. Click above the third test tube labeled “Protein Control (water)” to empty the water into
the tube.
4. Click on the container labeled “albumin” (eggs).
5. Click above the fourth test tube labeled “Test for Protein” to empty the albumin into the
tube.
6. A mixture of sodium hydroxide and copper sulfate is an indicator which tests for protein.
We will now use sodium hydroxide and copper sulfate to test for the presence of protein
in both the water and the albumin tubes. If protein is present, adding sodium hydroxide
and copper sulfate will turn the solution black. Place an eyedropper full of BOTH
sodium hydroxide and copper sulfate into the test tube labeled “Protein Control
(water)” and “Test for Protein”.
7. Use a different stirring rod for each test tube to mix the solution.
8. Record your answers in the chart below.
PROTEIN: Color Why?? EXPLAIN!
What color did the “Protein
Control (water)” turn?
What color did the “Test for
Protein” turn?
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Phase 3: Test for Lipids
1. Click on the pipette labeled “water”.
2. Click on the beaker labeled “H20” to pick up some water.
3. Click above the fifth test tube labeled “Lipid Control (water)” to empty the water into the
tube.
4. Click on the pipette labeled “lipid” and move it over the container labeled “vegetable oil” to
pick up some vegetable oil.
5. Click above the sixth test tube labeled “Test for Lipid” to empty the vegetable oil into the
tube.
6. Sudan III is an indicator which tests for lipids. We will now use Sudan III to test for the
presence of lipids in both the water and the vegetable oil tubes. If lipids are present,
adding Sudan III will turn the solution a BRIGHT red. Place an eyedropper full of Sudan
III into the test tube labeled “Lipid Control (water)” and “Test for Lipid”.
7. Use a different stirring rod for each test tube to mix the solution.
8. Record your answers in the chart below.
LIPID: Color Why?? EXPLAIN!
What color did the “Lipid
Control (water)” turn?
What color did the “Test for
Lipid” turn?
Phase 4: Test for Unknown
1. The unknown solution in this laboratory is a starch, protein or lipid. Your job is to
determine which macromolecules are present in the unknown.
2. Place an eyedropper of the unknown in each of the 3 test tubes labeled “Unknown”
3. Place an eyedropper of iodine into the test tube labeled “Unknown (starch)”.
4. Place an eyedropper of BOTH sodium hydroxide and Copper Sulfate into the test tube
labeled “Unknown (protein)”.
5. Place an eyedropper full of Sudan III into the test tube labeled “Unknown (lipid)”.
6. Use a different stirring rod for each test tube to mix the solutions.
7. Compare the color changes in the 3 unknown groups to the 3 control groups from phases
1-3 to see what macromolecules are present.
8. Record your answers in the chart below.
UNKNOWN: What macromolecule(s) are present
Test Tube | Color in the unknown solution? (circle)
Which test tube showed a
completely positive response to
an indicator solution?
Unknown
Starch Starch
Protein
Lipid
Unknown
Protein
Unknown
Lipid
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Phase 5: Test for Milk
1. The milk solution in this laboratory will respond most positively to one or more of the
indicator solutions. You will need to determine which compound(s) are present in milk.
2. Place a pipette of milk in each of the 3 milk-related test tubes.
3. Place an eyedropper of iodine into the test tube labeled “Milk (starch)”.
4. Place an eyedropper of BOTH sodium hydroxide and Copper Sulfate into the test tube
labeled “Milk (protein)”.
5. Place an eyedropper full of Sudan III into the test tube labeled “Milk (lipid)”.
6. Use a different stirring rod for each test tube to mix the solutions.
7. Compare the color changes in the 3 milk groups to the 3 control groups from phases 1-3 to
see what macromolecules are present.
8. Record your answers in the chart below.
MILK: What macromolecule(s) are present
Test Tube | Color in the milk?(Circle them BELOW)
Which test tube showed a
completely positive response to
an indicator solution?
Milk
Starch Starch
Protein
Lipid
Milk
Protein
Milk
Lipid
Post Lab Questions:
1. Looking at the control groups (water) for each macromolecule (starch, protein, lipid), does
water contain any of the three macromolecules?
2. Based on what you know about control groups, why did we use water as a control?
3. Now that you know the color changes that indicate the absence or presence of macromolecules,
answer the follow question.
If we ground up pepperoni pizza and tested it for each of the macromolecules,
what color would each test tube turn?
PIZZA
TEST TUBE COLOR of SOLUTION
Starch
Protein
Lipid