Cell Processes 8 Water bath at 25o C 50 ml of water in each cylinder
Method 1. Heat 150 ml of water to 25o
C.
2. Label the three graduated cylinders A, B and C. 3. Into A add 5 g of glucose and 50 ml of warm water (25o
C).
4. Into B add 5 g of artificial sweetener and 50 ml of warm water. 5. Into C add 50 ml of warm water but no food. This is a control experiment. 6. Add 1 g of yeast to each graduated cylinder and gently swirl to mix the contents. 7. Leave for 20 minutes in a 250
C water bath.
8. Observe what is happening inside the graduated cylinders. 9. Record the maximum level the foam rises to in each graduated cylinder.
Results
1. 2. 3.
Which cylinder produced the most foam? Did any cylinder not produce foam? What does this tell you about the relationship between the availability of glucose and the rate of respiration?
Glucose Artificial No Food Sweetener
Measure height of foam produced
Water Yeast Food
A
B
C Fig. 15 How the availability of glucose affects the rate of respiration.
Extended Investigation Plan, design and carry out an experiment to investigate the effect of one of the other factors on the rate of aerobic respiration in yeast cells: temperature, availability of oxygen or availability of water.
