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Potato Osmosis and Diffusion Lab Report

Emily Cocq

Research Question: Will there be a difference in the experimented potato cores after being subjected to high concentrations of sugar?

Introduction:

Water can move through protein channels in cell membrane/cell walls. The water will move due to the water potential of the cells. If there is a greater concentration of solutes (chemicals) inside the cell than outside the cell and the chemicals can not move, then water will respond by moving into the cell. This process involves water gradients called water potentials. If one area has a great deal of water, it has a high water potential. If an area has a great deal of dissolved material (less water) it has a low water potential. Water will attempt to move down it gradient, that is, from high to low water potential. You job is to observe this using potato cores that are placed into various solutions of sugar water. The sugar is too big to easily move through the cell membrane/cell wall. So, depending on the water potential of the cells VS the solution water will move in or out.

Hypothesis: If the potato cores are exposed to a higher concentration of sucrose in water, then

Variables:

Independent- Sucrose concentration of water

Dependent- Potato size

Controlled- Water level, size of cores, size of cups, type of potatoes

Materials:

Potato cores (4 per condition)

Sucrose solutions (.2, .4, .6, .8, 1.0)

Distilled water

Electronic balance

Plastic weighing tray

Plastic cups (6)

Graduated cylinder (50 ml)

Scalpel

Marking tape

Blue tweezers

Procedure:

1. Using marking tape, label 6 cups with the following solution types (.2, .4, .6, .8, 1.0 and Di water)

2. Place approximately 50 ml of the various solutions, each cup receiving a separate solution. Suggestion, measure the di water with the graduated cylinder, and fill the other cups to the same level

3. Obtain 24 potato cores and cut them to equal sizes (about 2.5 cm). All the cores you use must be the same length

4. Divide your 24 cores into 6 groups and gently blot them dry with a paper towel

5. Using the electronic balance and plastic weighing tray mass (weigh) each group of potato cores and record the data in a table that is labeled with a detailed title and which provides the error measurement of the electronic scale. MAKE SURE TO TARE THE TRAY. The table should record the type of solution in the cup and the mass of the potatoes in the cup.

6. Place the potato core sets in their appropriate cup and place in Mr. Boyers back prep room in the fume hood that is labeled with your block (3B or 4B).

7. PS make sure to indicate on your cup your group number, Mr Boyer will assign group numbers during the lab

8. 24 hours later you will need to come and measure the mass of your potato cores. To do this you must pour out the fluid in the cup and use the plastic blue tweezers remove the cores, blot them dry just as you did in the set up phase and final measure them using a plastic weighing tray. MAKE SURE TO TARE THE TRAY. Record your potato group mass on your data chart.

9. Finally dump your potato cores in the trash and wash and dry your equipment (cups, tweezers) and return them to their stations

10. Calculations. For each setup (all 6) you will need to calculate a percent mass change. To do this you will use the following formula (final mass-initial mass)/initial mass x 100. You will need to record this data in your data table as well. Make sure to keep track of the positive and negative changes if they occur

Data:

Potato Cores (Before Put In Water)

Cup

Error Measurement

Length

Mass

1 (Distilled Water)

0.05 g/cm

2.2 cm +/- 0.05 cm

2.4 g +/- 0.05 g

2 (0.2 % Sucrose)

0.05 g/cm

2.2 cm +/- 0.05 cm

2.4 g +/- 0.05 g

3 (0.4 % Sucrose)

0.05 g/cm

2.2 cm +/- 0.05 cm

2.4 g +/- 0.05 g

4 (0.6 % Sucrose)

0.05 g/cm

2.2 cm +/- 0.05 cm

2.4 g +/- 0.05 g

5 (0.8 % Sucrose)

0.05 g/cm

2.2 cm +/- 0.05 cm

2.4 g +/- 0.05 g

6 (1 % Sucrose)

0.05 g/cm

2.2 cm +/- 0.05 cm

2.4 g +/- 0.05 g

Potato Cores (After Put In Water)

Sucrose Concentration

Initial Mass

Final Mass

% Mass Change

Distilled water

2.4

2.6

8.33

0.2

2.4

2.7

12.5

0.4

2.4

2.3

-4.17

0.6

2.4

1.9

-20.8

0.8

2.4

1.8

-25

1

2.4

1.4

-41.67

Group 2 Results Graph (Our Group)

Results Graph- (All Groups)

Data (Of Other Groups)

Sugar Concentration

Group One

Group Three

Group 4

0

4.17

47.37

-19.23

0.2

4.17

-12

19.23

0.4

-8.33

8

-7.69

0.6

-18.18

8

-15.38

0.8

-29.06

27.78

-23.07

1

-43.40

-56.25

-38.46

Conclusion:

As the concentration of the sugar grew, the mass of the potato cores decreased. It moved from high water potential to low water potential, through the process of water gradients. Since the concentration was higher in the potato cores, the water tried to move out, to a lower concentration, in the sucrose water. This caused the potato cores to have a smaller mass.

The best-fit line touches the x-axis at around 0.3 sucrose concentration. Therefore, the water potential of the potato cores, or the solute concentration inside the potato cores, is 0.3%.

Evaluation/Reflection:

Evaluation 1: (What went right and well for you in the activity?)

In this activity, everything went smoothly and according to plan, and the entire group was efficient and on task. The materials were well-organized and put in place whenever needed.

Evaluation 2: (What difficulties did you encounter?)

We had no big difficulties or challenges during this activity, except that we forgot to take pictures for every step of the procedure. We did take photos at essential moments, but not at every step, so it may seem loose or shifting from exercise to exercise in the lab report.

Evaluation 3: (What new knowledge did you gain?)

I truly learned more about osmosis, concentration and cell membranes, and how they work in action. I was able to see the effects of materials moving

Evaluation 4: (What changes would you make next time to enhance the process or learning for yourself?)

The only change I would make to this activity if I were to do it differently another time, would be to have the procedure opened up in front of us, so we could see exactly when we needed to take pictures and when we did not. Other than that, everything else went perfectly according to plan.

Post-Pictures:

Potato Lab Data

8.3312.5-4.17-20.8-25.0-41.67

Sucrose Concentration

% Mass Change

Potato Lab

% of Mass Change G1SC 0SC 0.2SC 0.4SC 0.6SC 0.8SC 14.174.17-8.33-18.18-29.06-43.4% of Mass Change G2SC 0SC 0.2SC 0.4SC 0.6SC 0.8SC 18.312.5-4.17-23.83-25.0-41.67% of Mass Change G3SC 0SC 0.2SC 0.4SC 0.6SC 0.8SC 147.37-12.08.08.027.78-56.25% of Mass Change G4SC 0SC 0.2SC 0.4SC 0.6SC 0.8SC 1-19.2319.23-7.689999999999999-15.38-23.07-38.46

Sucrose Concentration

% Mass Change