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AP Biology Lab 4: Diffusion and Osmosis
PART A: Mystery Solutions
Problem: What is the concentration of various mystery solutions?
Experimental Set-up:
· 6 unknown colored solutions (0M, 0.2M, 0.4M, 0.6M, 0.8M, 1.0M Sucrose)
· 6 dialysis bags (cell models) filled with 5ml of 0.5M sucrose
· Weigh mass of bags before/after placing in 75ml of each mystery solution for 30 min.
· Calculate % Change in Mass
How can you determine the concentration of each solution? Explain your reasoning.
Data Table:
Analysis
· Calculate the % Change in Mass of dialysis tubes in each beaker.
· Determine the sucrose concentration in each mystery solution
· Graph the following:
§ % Change in Mass of Cell Model vs. Solution Sucrose Concentrations
Conclusion
How was the data used to determine the sucrose concentration of unknown solutions? Explain your reasoning.
(Use terms such as hypertonic, hypotonic, diffusion, osmosis, water potential, etc.)
PART B: Water Potential in Plant Cells
Problem: What is the water potential in various plant cells?
Inquiry:
Design an experiment to determine the water potential of various plant tissues.
Questions to guide investigation:
§ How can you measure the plant pieces to determine the rate of osmosis?
§ How would you calculate the water potential in the cells?
§ How does the water potential of different root vegetables compare?
§ How does the water potential of various fruits compare?
Materials:
Procedure:
Data Table:
Analysis:
§ Graph data (% Change in Mass vs. Sucrose Concentration)
§ Determine molar concentration of plant tissues
§ Calculate water potential of plant tissues
o Need to know: i, C, R, T
Conclusion:
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