Results
| Boiling tube | Temperature (oC) | Condition of lime water |
| A | 0 | Clear |
| B | 20 | Slightly cloudy |
| C | 35 | cloudy |
| D | 45 | Slightly cloudy |
| E | 65 | clear |
1. There is no activity in A as the temperature is too low for enzymes in the yeast to function whereas enzymes in the yeast in E are denatured as the temperature is too high.
2. When the yeast cells are more active, more carbon dioxide is produced. This causes the lime water to be more cloudy.
3. A lot of foam is produced.
Conclusion
Hypothesis is accepted. The activity of yeast is highest at an optimum temperature of 35oC.
Pg 97
| Boiling tube | pH | Condition of lime water |
| A | 5 | cloudy |
| B | 7 | Slightly cloudy |
| C | 9 | Clear |
1. The activity of yeast is very high in A because yeast works best in an acidic condition wheres the yeast cells were not active in C as it is alkaline.
2. The lime water turns cloudy faster than before because the medium for the reaction of yeast is now acidic.
Conclusion
Hypothesis is accepted. The activity of yeast is highest in an acidic condition of pH of 5.
Pg 98-99
| Boiling tube | Distance of light source (cm) | Condition of lime water |
| A | 20 | Clear |
| B | 30 | Slightly cloudy |
| C | 40 | cloudy |
| D | 50 | Very cloudy |
1. When the distance of the light source from the boiling tube increases, the lime water is more cloudy.
2. When the distance of the light source increases, the light intensity decreases.
Conclusion
Hypothesis is accepted. The lower the light intensity, the higher the activity of yeast.
Pg 99-100
| Boiling tube | Distance of light source (cm) | Condition of lime water |
| A | 20 | Slightly cloudy |
| B | 30 | cloudy |
| C | 40 | Very cloudy |
| D | 0 (distilled water) | Clear |
1. In C, there is a lot of foam whereas there is no foaming in D.
2. There is no activity in D as there is no nutrient. Activity of yeast increases when the concentration of glucose solution increases from A to C.
Conclusion
Hypothesis is accepted. The higher the concentration of nutrient, the higher the activity of yeast.
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