Direction and concentration gradients
Complete experiment 1, take a picture of you and your eggs to insert in the lab report, question 1, then fill out the data tables and answer the questions below.
Table 2: Water movement
Solution Type Volume (mL) Before Osmosis Volume (mL) After Osmosis Indicate change in volume
+ or - mL
100% distilled water
100% corn syrup
10% corn syrup/ 90% distilled water
Control
Table 2: Observations of Eggs After Osmosis
100% Distilled Water 100% Corn Syrup 10% Corn Syrup/ 90% Distilled Water Control
1. Include here a picture,, .jpg of you and your eggs:
2. Record your hypothesis from Step 15 here. Be sure to include scientific reasoning to support your predictions.
3. How do each of the three eggs placed in solution compare to the control egg?
4. For each beaker, identify whether the solution inside was hypotonic, hypertonic, or isotonic in comparison to the control beaker.
5. What was the direction of osmosis in the beaker labeled "100% distilled water"? Did the egg in this beaker burst?
6. Was there a volume in the "control" beaker after 24-48 hours? If so, why do you think this is? If not, why do you think this is?
7. Which solution contained a dehydrated cell? Think about someone having a high sugar diet. Hypothesize how their cells might be affected by osmosis?
8. Osmosis is how excess salts that accumulate in cells are transferred to the blood stream so they can be removed from the body active. Explain how this process works in terms of tonicity.
Experiment 2: Tonicity and the Plant Cell
Complete Experiment 2 procedure from the lab link and complete the following tables and answer the questions.
Table 3: Water Displacement per Potato Sample
Potato Type Potato Observations Sample Initial Displacement (mL) Final Displacement (mL) Step 11 Net Displacement (mL)
+ or -
Sample 1
( your potato type here) A
Sample 1 B
Sample 2
( your potato type here) A
Sample 2 B
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.