Diffusion and osmosis experiment 4: osmosis – tonicity and the plant

Data Tables and Post-Lab Questions

Table 7: Water Displacement per Potato Sample

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 cells (potato cells) in each of the samples examined? How do you know this? 

6. Would this experiment work with other plant cells? What about with animal cells? Why or why not? 

7. From what you know of tonicity, what can you say about the 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 more likely to absorb more or less water? Explain.