Aerobic Cell Respiration: Germinating Peas in Phenol Red
Purpose: The purpose of this investigation is to introduce the student to the process by which most cells burn glucose with oxygen, a process called aerobic cell respiration. Germinating peas are an ideal organism for this experiment because they are growing rapidly and are burning the sugar that is stored in the seed.
Materials and Methods: The materials required for this experiment are germinating peas, dormant peas, four test tubes, test tube rack, 50 ml beaker, phenol red, hot plate, straws.
Cut some straws and place the pieces into the bottom of each test tube. Pour phenol red into each test tube just below the straws. The straws will keep the peas out of the phenol red. Kill some of the germinating pea seedlings by boiling them in a beaker of water.
Experiment: Number each of the test tubes and set them up in the following manner:
Test tube one contains only phenol red.
Test tube 2 contains dead peas.
Test tube 3 contains dormant peas.
Test tube 4 contains germinating peas.
Insert a cork into each tube and allow the experiment
to sit undisturbed overnight.
Conclusion: Write an equation for aerobic cell respiration in the table below:
What gas is given off by the germinating peas as they burned the glucose?
Examine the reaction below:
| CO
+ H O ---------> H CO --------->
H+ + HCO
- 2 2 2 3 3 |
Phenol Red turns yellow under acid conditions. The reaction shown above creates the acid conditions that may occur in this experiment. With that in mind, what happens to the phenol red in each tube? Explain why.