THE LIVER LAB: How Do Cells React to Changes in Ph

Name ______Date: ______Class Period ______THE LIVER LAB: How do cells react to changes in pH?

Organisms require very specific conditions in order to live, the right temperature, hydration, amount of light, and pH etc. Living cells need to remain within a neutral pH. If they are subjected to acidic or basic conditions, the cell will die. In this laboratory exercise we will observe how cells adapt to changes in pH. We will also be looking at different ways to measure pH and how to get the most accurate measure of pH. Theory: In order to understand the theory behind this laboratory you will need to define the following terms. Acid, Base, Biological Buffer, pH, pH scale, Ions, H+, OH-

Materials: Equipment:

0.1 M HCl pH Paper 0.1 M NaOH pH Probe with Laptop Distilled Water Beakers Liver Solution Forceps

CAUTION: Be sure that you understand the proper use and care of the pH probe before you start this lab. This will be demonstrated by your instructor.

Procedure:

Part A: How do acids and bases change the pH of water?

1. Place 50mL of distilled water into two beakers. Label one beaker acid and the other one base. 2. Take the pH of your water. Record in data table. 3. Add one drop of acid to the acid beaker and one drop of base to the base beaker. Swirl the beakers to mix the contents. 4. Use the pH paper and the pH probe to test the pH. Record your result in your data table. 5. Next, Add 5 more drops to the beakers and record the pH. 6. Continue to add acid and base to the respective beakers until you’ve reached a total of 31 drops added. It is essential that you SWIRL EVERYTIME!!! 7. Record your results

Part B: How do Living Cells react to the addition of acids and bases?

Repeat the procedure above, using two beakers with 50 ml of liver solution provided by your teacher.

You must be sure to clean the pH probe at the end of this lab. Leaving liver solution on the pH probe will destroy the probe. Data Tables Table 1: pH of water with acid and base Table 2: pH of liver with acid and base pH Acid + pH Base + pH acid + pH base + Drops added liver Liver water water Drops Added Paper Probe Paper Probe Paper Probe Paper Probe 0 0 1 1 6 6 11 11 16 16 21 21 26 26 31 31

Analysis: 1. Construct a line graph of these results. You need one graph with four lines. Use a legend to show which line represents which data.

2. Compare the 2 methods of testing pH. What were the advantages and disadvantages of each method? ______

3. What happens to the concentration of H+ ions as the pH decreases? ______

4. What happens to the concentration of OH- ions as the pH decreases? ______

5. How does the pH change when acids or bases are added? ______

6. What is the relationship between H+ and OH- ions and the pH scale? ______Complete the “Liver Lab Conclusion” handout.