AP Biology 2013
Tokos/Dannenberg
Diffusion and Osmosis Lab
Pre Lab Questions: Part 1
1. What is the surface area of a cube that measures 1.5 cm on each side?
2. What is the volume of a cube that measures 1.5 cm on each side?
3. Name a physical factor that affects the rate of diffusion and give an example to demonstrate the relationship.
Pre Lab Questions: Part 2
1. Define the terms solute, solvent, and solution.
2. How many grams of sucrose would you add to 100mL of water to prepare a 5% solution by mass? (Hint: you will need to know the density of water.)
3. How many grams of sucrose would you add to 100mL of water to prepare a 5 M solution?
4. Define diffusion
5. Define osmosis
6 . Write the formula for water potential. What variable does “s” represent? What variable does “p” represent?
7. The water potential of a solution in a dialysis bag depends only on solute potential. Explain why.
8. Calculate the solute potential of a 0.1 M NaCl solution at 25°C.
9. While holding pressure constant, increasing solute concentration increases or decreases the water potential number (circle one).
10. Circle the correct phrase:
Water will go from an area of -3 water potential to 0.
Water will go from an area of 0 water potential to -3.
11. A dialysis bag contains a sucrose solution of 0.6M. The beaker into which it is placed
has a sucrose concentration of 0.3M. Is the dialysis bag hyper- or hypotonic to the beaker
solution? ______. In which direction is the water expected
to travel? ______Name a sucrose solution concentration that
would be isotonic with the solution in the dialysis bag ______.
12. What is meant by the term “gradient” as it applies to diffusion?
13. Fill in the blanks: water moves across a semi-permeable membrane from an area of
______water potential to an area of ______water potential.
14. Define the term “lysis.”
15. Research the meaning of hyponatremia.
16. Explain why a patient who requires fluid replacement receives a salt solution (saline), not pure water.
Pre Lab Questions: Part 3
1. While holding solute concentration constant, increasing pressure increases or decreases the water potential number (circle one).
2. What is meant by the term “turgid” as it applies to a plant cell?
3. Define turgor pressure.
4. What are the two plant cell structures that help maintain turgor pressure?
5. Define the term plasmolysis.
6. Pressure potential at atmospheric pressure is defined as zero. Plant cells typically are immersed in a hypotonic environment relative to the contents of the cells themselves. In order to maintain osmotic equilibrium with the environment, will the turgor pressure be a positive number or a negative number? Explain your reasoning.