Investigating The Effect Of Temperature On The Respiration Of Yeast

by grantyimhkgmailcom (student)

Grant Yim

L6EP

Investigating The Effect Of Temperature On The Rate Of Respiration Of Yeast

Table showing the effects of temperature on the rate of respiration of yeast

Conclusion

To conclude, it can be identified from the results that as temperature increases, the rate of respiration of yeast also increases. The rate of which respiration increases doubles with every 10°C increase in the temperature, the theory which identifies this trend is called Q2. Examples of this trend can be seen with an increase in temperature from 10°C to 20°C; which resulted in an increase in the average rate of reaction from 0.039 to 0.067, that is an 75.67% increase in the rate of reaction. The same applies from 20°C to 30°C and from 30°C to 40°C, with 65.3% and 101% increases in rate of respiration respectively. This increased in rate of respiration is due to the increased kinetic energy within the glucose-yeast solution. With more kinetic energy in the molecules, cellular reactions are carried out with more successful collisions (molecules joining with the enzyme’s active site) at a more frequent rate, which increases the rate of reaction, increasing the rate of respiration. This is also reflected by the positive gradient of the graph.

However when the temperature increases from 40°C to 50°C, Q2 no longer applies which is reflected in the results. Showing the average rate of respiration increase from 0.210 to 0.239, this is due to the denaturing of the enzymes in the yeast signifying cellular rate of respiration decreasing. The enzyme’s optimum temperature is at 37°C, and starts denaturing at around 42°C; yeast contains enzymes which are required to carry out anaerobic respiration. When the temperatures reaches around 40°C, the active enzyme cell deforms and the hydrogen bonds break due to the increased kinetic energy, denaturing the yeast enzyme meaning ...

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Limitations of Experimental Design

Firstly, there was difficulty keeping the temperature of the water-bath constant throughout the experiment, this is partly due to the fact that the thermometer wasn’t sensitive enough, it could only measure accurately to the nearest 0.05°C and wasn’t very responsive to the constant changes in temperature. Furthermore the temperature of the water-bath kept fluctuating within a 2-3°C range which tampers with the reliability of our results.

Secondly, for the experiment, the same source of yeast was used throughout the whole process of experimenting, meaning that the respiring batch of yeast in the water bath could have potentially already respired all the glucose in the solution, which means that the rate of respiration for each test could be potentially lower than the next due to this factor.

Thirdly, the apparatus we used wasn’t assembled properly, which suggests human error could be a potential factor. There were gas leaks in our apparatus, which signified that not all the C02 given off by the anaerobically respiring yeast was collected in our measuring cylinders.

A significant anomalous is identified as the 50°C test 1, with a significant reading of 2.4cm3 of C02 given off, the culmination of the above errors could have contributed to this and also the slight difference of inconsistent readings littered throughout our results table.

Suggestions For Improvement

Temperature is a major variable to have control of, it is a variable we are testing for and hence we have to narrow down the marginal error that could potentially occur; as it may have a significant impact on our results. A change to our apparatus, making use of an electric thermometer which is more accurate and responsive to a change in temperature can reduce the error threshold from + 0.05°C to +0.005°C. Furthermore the ‘water bath’ ought to be an electric heated basin which can keep the temperature constant to the nearest + 0.5°C, which eliminates the possibility of temperature fluctuations bigger than +2-3°C. This would greatly impact our results providing more consistent, more accurate and reliable data.

The same source of yeast could potentially run out of glucose to respire from, a way to improve on this is increase the number of simultaneous experiments taking place. Our current method suggests one student do 3 tests for one temperature, each test lasts 7 minutes. If we triple the number of students, then all tests could potentially be carried out at the same time and hence the % glucose left in the yeast-glucose solution would all be constant. However with more students to carry out the tests, it signifies an increase in the chance for human error to occur. But the significance of the test being conducted at the same time is a bigger advantage contributing to a fairer test than increasing the probability of human error.

The apparatus in the experiment is very important; gas leaks caused by old rubber tubing would affect the results we obtain massively, because the volume of C02 produced is what we are measuring. It is possible to suggest that we re-new our equipment, which prevents the possibility of apparatus failure or the ineffectiveness of the apparatus. All of which contributes to the consistency of the data we collect.

If these 3 major issues are addressed, it will significantly reduce the probability or the potential for error to occur, our results will therefore be more reliable and accurate and maybe the theory of Q2 will become more prominent. Because of the potential gas leak problems and fluctuating temperatures, we were unable to achieve a clear demonstration of the Q2 theory. When temperature increases, rate of reaction should double, but our results reveal that it ‘almost doubles’. And I think that if the issues mentioned earlier are addressed, then the rate of reaction increasing per 10°C will no longer be 75.67% or 65.3% but 100% + 1%.