Alcoholic fermentation is a metabolic pathway used primarily by yeast and some bacteria. In fermentation, glucose is broken down into ethyl alcohol (ethanol) and carbon dioxide. In the process, some of the energy that had been stored in the glucose bonds is used to form high energy bonds in ATP. Name some factors that affect enzyme activity.
Temperature, pH, enzyme concentration, substrate concentration
Materials: yeast, test tubes, beakers, rubber stoppers, wax pencil, water, corn syrup
1. You will need to have three fermentation setups, so you should have six large test tubes, three pieces of plastic tubing that ...view middle of the document...
Swirl each test tube gently to mix the reactants. Place one test tube in each beaker.
10. Put the rubber stoppers in the fermentation tubes. This will force most of the water out of the tubing.
11. After the air bubbles from inserting the stopper have cleared the tubing, mark the water level on each collection tube with a wax pencil. This marks the baseline for your experiment.
12. At 5-minute intervals, measure (in mm) the distance from the baseline mark to the water level. Continue taking data for at least 20 minutes. Record your data in Table 6.2.
Tube | Minutes |
| 0 | 5 | 10 | 15 | 20 | 25 | 30 |
1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
2 | 0 | 13 | 13 | 20 | 20 | 20 | 20 |
3 | 0 | 10 | 12 | 18 | 20 | 20 | 20 |
While you are waiting to collect data, look again at Table 6.1 to see how the experiment was designed. What is the independent variable?
What is the dependent variable?
Amount of CO2 in millimeters
What hypothesis is being tested?
The more yeast added, the more CO2 produced
Predict the outcome of the experiment in terms of your hypothesis. Explain what results would support your hypothesis.
In Tube 3, there will be more CO2 than the rest of the tubes. Tube 2 will have the second most. Tube 1 will have the least amount of CO2.
Was your hypothesis proven false or supported by the results? Use data to support your answer.
Which fermentation tube was the control?
Why were different amounts of water added to each fermentation solution?
Because we needed to keep the consistency of 7 mL of solution per tube
What are some other independent variables that could affect alcoholic fermentation?
Water temp, room temp, lighting
Measuring Photosynthetic Rate in Spinach Leaf Disks
Materials: lamp, support stand, spinach leaves, cork borer, petri dishes, water, plastic tubing, water aspirate, NaHCO3
1. Attach the lamp to the support stand so that the lamp is approximately 25 cm from the base of the stand.
2. Fill a large beaker with cold water to act as a heat filter for the dish you will place under the lamp. The lamps produce a lot of heat, which can affect the rate of photosynthesis. Set the beaker aside for the moment.
3. Pour 0.2% NaHCO3 solution into three petri dishes so they are about 2/3 full. Pour approximately 100 mL of 0.2% NaHCO3 solution into a 250-mL flask. The exact amount is not important, so you can use the markings on the flask to measure.
4. Get several spinach leaves and cut 40-50 disks with a cork borer or other...