Bio Yeast Reaction Rates
3A Task 1
Aim: the aim of the experiment is to find the best temperature to ferment yeast at.
Hypothesis: the yeast will ferment the best at 60 degrees Celsius.
Independent variable: the temperature of the water the yeast is put in to ferment.
Dependent variable. The amount of air bubbles the yeast produces.
Controlled variable: the amount of yeast and glucose in each syringe.
Uncontrolled variables: human error in counting.
Materials : Plastic soft drink bottle cut to size
Marking pen
3 syringes
Stopwatch
3 stoppers
3 large ball bearings
20% glucose solution
3 grams of yeast
Thermometer
Digital balance
3 X 10 mL measuring cylinder
Procedure:
1. Three students in each group will set up syringes as per diagram and number these 1, 2 or 3. Each student will be responsible for one of the three syringes in the water bath. 2. The fourth student is responsible for filling up the plastic drink bottle with the correct water temperature. This must be done before part 4. 3. Once the soft drink bottle is filled at the correct temperature, it is the responsibility of student 4 to maintain this temperature by adding or subtracting hot water or ice. They are also the designated timer for the other three students. 4. Once the drink bottle reservoir is ready, the other three students must complete this section together. To each syringe, add 10 mL of 20% glucose solution and one gram of yeast. Stir the contents by shaking the syringe with both ends blocked, one with a stopper and the other with a finger. This must all be done in one minute. 5. Place all three syringes in the water, stopper facing down and narrow section pointing up. 6. Once they are all in place, allow 3 minutes to pass. 7. Now count the number of bubbles released per minute from each syringe for the next 10 minutes and record in a draft table. 8. Collate your groups result as three trials over 10 minutes and
Aim: the aim of the experiment is to find the best temperature to ferment yeast at.
Hypothesis: the yeast will ferment the best at 60 degrees Celsius.
Independent variable: the temperature of the water the yeast is put in to ferment.
Dependent variable. The amount of air bubbles the yeast produces.
Controlled variable: the amount of yeast and glucose in each syringe.
Uncontrolled variables: human error in counting.
Materials : Plastic soft drink bottle cut to size
Marking pen
3 syringes
Stopwatch
3 stoppers
3 large ball bearings
20% glucose solution
3 grams of yeast
Thermometer
Digital balance
3 X 10 mL measuring cylinder
Procedure:
1. Three students in each group will set up syringes as per diagram and number these 1, 2 or 3. Each student will be responsible for one of the three syringes in the water bath. 2. The fourth student is responsible for filling up the plastic drink bottle with the correct water temperature. This must be done before part 4. 3. Once the soft drink bottle is filled at the correct temperature, it is the responsibility of student 4 to maintain this temperature by adding or subtracting hot water or ice. They are also the designated timer for the other three students. 4. Once the drink bottle reservoir is ready, the other three students must complete this section together. To each syringe, add 10 mL of 20% glucose solution and one gram of yeast. Stir the contents by shaking the syringe with both ends blocked, one with a stopper and the other with a finger. This must all be done in one minute. 5. Place all three syringes in the water, stopper facing down and narrow section pointing up. 6. Once they are all in place, allow 3 minutes to pass. 7. Now count the number of bubbles released per minute from each syringe for the next 10 minutes and record in a draft table. 8. Collate your groups result as three trials over 10 minutes and