Diffusion and concentration gradients
Table 6: sucrose concentration vs. tubing permeability
1. For each of the tubing pieces, identify whether the solution inside was hypotonic, hypertonic, or isotonic in comparison to the beaker solution it was placed in.
2. Draw a picture of a cell in isotonic, hypotonic, and hypertonic states.
3. What is the potential of an open beaker containing pure water?
4. Why don't blood cells swell or shrink in blood?
5. How do osmotic power plants work?
6. Research the structures that protect plant and animal cells from damage resulting from osmotic pressure. Write a few paragraphs explaining what they are, how they work, and where they are located.
2. Which tubing increased the most in volume? Why?
3. What does this tell you about the relative tonicity between the content of the tubing and the solution in the beaker?
4. What would happen in the tubing with the yellow band was placed in the beaker of distilled water?
5. Osmosis is how excess salts that accumulate in cells are transferred to the blood stream so they can be removed from the body. Explain how this process works in terms of tonicity.
6. How is the experiment similar to the way a cell membrane works in the body? How is it different? Be specific with your response.
7. If you wanted water to flow out of a tubing piece filled with a 50% solution, what would the minimum concentration of the beaker solution need be? Explain your answer using scientific evidence.
Experimemt 4: osmosis- tonicity and the plant cell
Post- lab questions
1. How did the physical characteristics of the potato vary before and after the experiment? Did it vary by potato type?
2. What does the net change in the potato sample indicate?
3. Different types of potatoes have varying natural sugar concentrations. Explain how this may influence the water potential of each type of potato.
4. Based on the data from this experiment, hypothesize which potato has the highest natural sugar concentration. Explain your reasoning.
5. Did water flow in or out of the plant cell (potato cells) in each of the samples examined? How do you know this?
6. Would this experiment work with other plant cells? What about animal cells? Why or why not?
7. From what you know of tonicity, what can you say about plant cells and the solutions in the test tubes?
8. What do your results show about the concentration of the cytoplasm in the potato cells at the start of the experiment?
9. If the potato is allowed to dehydrate by sitting in open air, would the potato cells be likely to absorb more or less water? Explain.
10. Compare and contrast diffusion and osmosis.