Data/Answer Sheet for AP LABORATORY #1: DIFFUSION and OSMOSIS

Data/Answer Sheet for LAB “A”: DIFFUSION AND OSMOSIS EXERCISE 1A: Diffusion

Data Table 1:______

Initial Contents Solution Color Presence of Glucose (Y or N) Initial Final Initial Final Bag 15% glucose & 1% starch

Beaker H2O + IKI

Draw your lab set up using the template below.

semipermeable membrane of dialysis tubing ______(inside tubing)

______(outside tubing)

Analysis of Results for Lab A: Diffusion 1. Which substance(s) are entering the bag?

Which substance(s) are leaving the bag?

What experimental evidence supports your answers above (use your data above!)?

2. Explain the results you obtained. Include the concentration differences and membrane pore size in your discussion.

3. Quantitative data uses numbers to measure observed changes. How could this experiment be modified so that quantitative data could be collected to show that water diffused into the dialysis bag (Think: how would you know if water was gained or lost)?

4. Based on your observations, rank the following by relative size, beginning with the smallest: glucose molecules (C6H12O6), water molecules (H2O), IKI molecules, membrane pores, starch molecules. (HINT: Use molecular mass to determine size.)

5. What results would you expect if the experiment started with a glucose and IKI solution inside the bag and only starch and water outside? Why? LAB “B”: Osmosis 1) In Experiment 1B, identify:

IDV: ______(be detailed & specific when you name this)

DV: ______(what data did you directly collect)

Percent Change in Mass = Final Mass – Initial Mass x 100 Initial Mass 2) EXPERIMENTAL RESULTS Data Table 1: (Be sure your title includes the DV & IDV) Data Table 2: (Be sure your title includes the DV & IDV)

3) Graph the results for average percent change in mass of the various dialysis bags. (HINT: Don’t forget to include: complete title and the x & y axis labels with units. Your x axis label needs to completely describe what is being graphed. The units only go next to the label, not next to each number.

4) CONCLUSION (A template has been provided to help you write a formal conclusion. Write the prompt and then continue writing. Conclusions are written as an essay. Do not use bullet points):

In this lab we tried to answer the question:

As a class, we found (include summary of what happened and the class averages with units)

Biologically, these results occurred because (Think: Why did the water move into or out of the dialysis bags at each concentration?)

Two sources of error which affected our class average include . (Be sure to explain why it is an error. What does the error do to your data? Remember- errors should be errors in procedure/design, not how your group didn’t/couldn’t follow the procedural design!)

We could fix each of these errors by (provide realistic modifications to your stated errors & include how your fix would correct for the error)

5) FOLLOW UP QUESTIONS: Just answer these questions; it is not necessary to write out the question. 1. Why did you calculate the percent change in mass rather than simply using the change in mass?

2. A dialysis bag is filled with distilled water and then placed in a sucrose solution. The bag’s initial mass is 20 g, and its final mass is 18 g. Calculate the percent change of mass, showing your calculations in the space below.

semipermeable membrane 3. Which direction would the water flow in the distilled water (inside tubing) diagram on the right? 0.2 M sucrose (outside tubing)