To study the population growth rate of yeast, a microorganism Saccharomyces cerevesiae
| | Units|
Independent variable| Time the readings were taken| Hours| Dependent variable| Absorbance (increasing yeast population)| -|
Controlled variables| Units| Possible effects on result| The wave lengths| Nanometer| since the transmission and absorbance is being measured at a specific wave length, so if we change it the results will also change| The amount of mixture in cuvette| ml| if we filled the cuvette with the mixture then there could be chances of the mixture spilling due to the reason that they were fermenting| Cleanliness of the cuvette| | if the cuvette is not clean then it will affect the transperancy|
As the time increases the level of absorbance increases and the % transmission decreases in the yeast population.
2 - medium sized test tube
20-ml apple juice
Few paper and paper towels
1 - gram Dry super active yeast
2 - square plastic cuvette
1 - Electronic balance
1 - Spectrophotometer.
Table 1: showing the % transmission and the absorbance of the solution at the hour mentioned inthe column of time. time| % transmission| absorbance|
0| 19| 0.72|
3| 23| 0.64|
5.4| 23| 0.64|
17.21| 24| 0.62|
21| 24| 0.62|
24| 24| 0.62|
40.45| 6| 1.22|
45.45| 9| 1.05|
46.38| 4| 1.4|
Graph 1: showing the results for table 1.
My hypothesis that, as the time increases the level of absorbance increases and the % transmission decreases in the yeast population, is not supported by my results. This can be seen in graph 1 where we see that at start the absorbance decreases but as time increases, the absorbance increases and we see exponential growth in the population of yeast i.e. we can see from table 1 when the results were taken at the very first...