🧪 Virtual AP Biology Lab: Testing for Biological Molecules
Interactive Simulation - Perform tests virtually
Skill Focus: Experimental design, data collection, analysis
Status:Ready to start
👤 Student Information
Lab Instructions
1. Select a test tube from the rack
2. Add Benedict's reagent to the test tube
3. Click "Perform Benedict's Test"
4. Click "Apply Heat" to see the color change
5. Record your observations in the results table
Select Sample
Add Reagent
Perform Test
Apply Heat
Hot Water Bath
Water
Glucose
Starch
Egg White
Oil
Reagents
Click to add reagent to selected test tube
💧
Benedict's Solution
💧
Iodine Solution
💧
Biuret Reagent
💧
Sudan III
Test Controls
📊 Test Results
Sample
Benedict's Test
Iodine Test
Biuret Test
Sudan Test
Observations
Water
-
-
-
-
-
Glucose
-
-
-
-
-
Starch
-
-
-
-
-
Egg White
-
-
-
-
-
Oil
-
-
-
-
-
💬 Discussion & Analysis Questions
Answer these questions based on your experimental results and knowledge of biological molecules:
1
Explain why glucose produced a positive result with Benedict's test while starch did not, despite both being carbohydrates.
Hint: Consider the chemical structure differences between monosaccharides and polysaccharides, and what makes a sugar "reducing."
2
Describe the molecular basis for the color change in the Biuret test. What specific chemical groups are detected?
Hint: Think about the peptide bonds and how copper ions interact with them.
3
Why is distilled water used as a control in these experiments? What would it mean if the water control showed a positive result for any test?
Hint: Consider the purpose of controls in experimental design and potential sources of contamination.
4
Based on your results with milk, explain why it showed positive for multiple macromolecule tests. How does this relate to its biological function?
Hint: Consider the nutritional composition of milk and its role in mammalian development.
5
How does the chemical structure of lipids explain their hydrophobic nature and the results observed in the Sudan III test?
Hint: Think about the proportion of polar vs. nonpolar regions in lipid molecules.
6
Design an experiment to quantify the concentration of protein in an unknown solution using the Biuret test. What controls would you need?
Hint: Consider creating a standard curve with known protein concentrations.
7
Explain how the structure of each macromolecule relates to its biological function, using specific examples from your experimental results.
Hint: Connect molecular structure (monomers, bonds, 3D shape) to function (energy storage, structural support, information storage, etc.)
8
If you tested a sample of human blood plasma, predict which macromolecules would be present and explain their functions in the bloodstream.
Hint: Consider albumin, antibodies, lipoproteins, and glucose transport.
9
How might the results of these tests differ if you used plant tissues (like potato, onion, or avocado) instead of the samples provided?
Hint: Consider the storage molecules and structural components in different plant tissues.
10
Explain why enzymes (which are proteins) are sensitive to temperature and pH changes, relating this to the protein structure you observed in the Biuret test.
Hint: Consider how temperature and pH affect hydrogen bonding and protein conformation.