1. LAB: Macromolecule Virtual Lab
HONORS BIOLOGY: UNIT 1
GRADING RUBRIC
TOTAL POINTS = 60

2. Background: The most common organic compounds found in living organisms are lipids, carbohydrates, proteins, and nucleic acids. Common foods, which often consist of plant materials or substances derived from animals, are also combinations of these organic compounds.
Substances called indicators can be used to test for the presence of organic compounds. An indicator is a substance that changes color in the presence of a particular compound. In this investigation, you will use several indicators to test for the presence of lipids, carbohydrates, and proteins in various foods.

3. CARBOHYDRATES Scroll down to the bottom and click on Carbohydrate
What are some examples of carbohydrates?
Examples of sugars are glucose, sucrose, maltose, etc.
Polysaccharides include storage carbohydrates such as plant and animal starches, and structural carbohydrates like cellulose (plant fiber) and chitin (insect skeletons).
2 POINTS

4. 2. How do you test for sugars?
Benedicts Reagent test- turns from blue → green → yellow → orange → red
2 POINTS

5. 3. Draw the lab set up and label the different test tubes.
2 POINTS

6. ►Click on Add Benedict’s Reagent
Add 10 drops of Benedict’s solution to each test tube. When heated, Benedict’s solution will change color from blue to green, yellow, orange, or red in the presence of a simple sugar, or monosaccharide. The more sugar present, the more orange/red the solution should be.
►Click on Add Benedict’s Reagent
1. What was the color of each test tube (tt)?
tt1 blue
tt2 blue
tt3 light green
tt4 light blue
tt5 blue
2 POINTS

7. ►Click on Hot Water Bath
In your diagram above, shade in the test tubes that showed a positive test for sugar.
2. Which solutions changed colors after heating in hot water bath? Glucose, onion juice potato juice
BEFORE
AFTER
2 POINTS

8. By its color (blue → green → yellow → orange → red)
3. Which test tube had the greatest amount of sugar in it? How did you know?
Glucose had the most.
By its color (blue → green → yellow → orange → red)
2 POINTS

9. What chemical is being added to the test tubes? Iodine (Lugols)
Add 5 drops of iodine solution to iodine each test tube. Iodine will change color from yellow-brown to blue-black in the presence of starch.
►Click on the scroll down bar on the right hand side and go to starches
What chemical is being added to the test tubes?
Iodine (Lugols)
2 POINTS

10. 2. What should happen if starch is present ?
A color change from yellow or brown to a blue-black color indicates that starch is present.
2 POINTS

11. Which solutions changed colors? Starch and Potato juice
►Click on Add Iodine
Which solutions changed colors?
Starch and Potato juice
BEFORE
AFTER
2 POINTS

12. ►Click on the tab marked protein
PROTEINS
Add 5 drops of biuret reagent to each test tube. Biuret reagent changes color from yellow to blue-violet in the presence of protein.
►Click on the tab marked protein
What are the building blocks that make up proteins?
Amino acids
2 POINTS

13. 2. What test do we use to test for proteins?
Biuret Reagent- change from blue to violet means proteins are present.
2 POINTS

14. 3. Draw and label the test tubes for the demonstration
2 POINTS

15. ►Click on Add Biuret Reagent
In your diagram above, shade in the test tubes that showed a positive test for protein.
What solutions changed color?
Egg white and chicken soup
BEFORE
AFTER
2 POINTS

16. It means that proteins are present
2. What does it mean?
It means that proteins are present
2 POINTS

17. ►Click on tab marked Lipids
Sudan III stain will dissolve in lipids and stain them red or orange.
What test is used for lipids?
Sudan III - a vivid orange color should appear.
2 POINTS

18. 2. How does it work?
As fat content increases, the intensity of the dye (Sudan III) also increases - a vivid orange color should appear.
2 POINTS

19. 3. What color do the solutions change if lipids are present?
Vivid orange
2 POINTS

20. What solutions changed colors? Margarine, cream, and coconut
►Click on add Sudan III
What solutions changed colors?
Margarine, cream, and coconut
2 POINTS

21. It means that Margarine, cream, and coconut contain lipids
2. What does this mean?
It means that Margarine, cream, and coconut contain lipids
2 POINTS

22. EVERYDAY FOODS
►Click on the tab marked Everyday Foods
Run the tests on each of the everyday foods. In the data table below. Record the color of the test tube AFTER the test was run, and place a check mark in the boxes that showed a positive test.
For the other foods in the data table, predict which tests would you expect the food to test positive for and what color results you would get.

23.    6 POINTS   NO NO Violet YES Red YES Black Orange
Data Table
Substance
Lipid Test
Carbohydrate Test
Protein Test
Sudan color
Lipids present (Yes or No)
Iodine color
Starches present (Yes or No)
Benedict’s color
Sugars present (Yes or No)
Biuret color
Proteins present (Yes or No)
Gelatin
NO 
 NO
 Violet
YES 
Apple juice
 Red
 YES
Ritz cracker
 Black
Skim milk
 Orange
For the foods below, PREDICT which macromolecules they would test positive for.
Bacon  
 violet
  
Candy
red  
Corn oil
Orange
Bread
  
Blue
black 
Honey
 red
water
Chicken
violet 
Pasta
 Blue
black
  
6 POINTS

24. Analysis Questions:
1. Match the molecule to the chemical used to test for it to the color that the chemical would change for a positive test. (draw lines to connect)
Macromolecule Reagent Color Change
Sugar Biuret Reagent Green, Orange, or Red color
Protein Sudan III Blue-black color
Lipid Iodine Red or Orange color
Starch Benedict’s Solution Blue-Violet color
4 POINTS

25. 2. Which substances contained a protein? Gelatin and skim milk
Predictions: Bacon, bread, chicken, and pasta
1 POINTS

26. 3. Which substances contained lipids? Margarine, cream, and coconut
Predictions: Bacon, corn oil, bread, and chicken
1 POINTS

27. 4. Which substance contained sugars? Apple juice and skim milk
Predictions: Candy and honey
1 POINTS

28. 5. Which substances contained complex (large) carbohydrates?
Starch and Potato juice
Ritz cracker and skim milk
Predictions: Bread and pasta
1 POINTS

29. 6. How are the reagents useful in determining which macromolecules are present?
A color change indicates the presence of different substances. In some cases the color can vary indicating the amount of the substance present
2 POINTS

30. It means lipids and proteins are present.
7. A very thin slice is removed from a peanut and treated with Sudan III stain. Then a drop of Biuret reagent is added to the peanut slice. When you examine the peanut slice under a microscope, patches of red (organge) and blue-violet are visible. What conclusions can you draw from your examination?
It means lipids and proteins are present.
2 POINTS

31. 8. A cracker crushed in water will test positive with iodine but negative with benedict’s solution. A cracker crushed in water has another chemical called amylase added to it. After a few minutes, this cracker tests negative with iodine and positive with benedict’s solution. Explain what happened.
When amylase (an enzyme) was added it broke down the starch (complex carbohydrate) into a simple sugar. Now only sugar is present
2 POINTS

32. It will also still test positive for proteins
9. Whole milk does not have any of the fat removed from it that skim milk does. What changes would you expect in tests run on whole milk compared to the results received from skim milk?
When tested with Sudan III for lipids, the color should be more intense orange.
It will also still test positive for proteins
2 POINTS

33. TOTAL POINTS = 60