Investigate which sugars the yeast can respire.

1. Measure out 5 cm3 of Sugar solution in a measuring cylinder, obtained from a beaker containing the sugar solution, extracted using a pipette, and put into one of the conical flasks
2. Measure 10 cm3 of yeast solution using a measuring cylinder, obtained from a beaker containing the yeast solution, and place into the conical flask.
3. Measure the weight immediately after you mix these two solutions.
4. Leave the solution overnight.
5. Measure it again the next day, and record any changes.
6. Repeat the experiment another two times, to make it a fair test.
7. We will take in the results from the class for the results of the other sugars

Fair test

To make it a fair test, I am going to make sure that I always use the same amount of sugar solution each time – 5 cm3 – and make sure that the amounts of yeast put into the conical flask is always exact, that is, 10 cm3. I will also make sure that the measuring cylinder and conical flask are always washed before use. Also, I will make sure that the same person is pouring out the solution in our group, and the same person is placing the yeast and sugar solution in the conical flask. We will repeat this experiment at least twice, if not three times, to make sure that the results we obtain are accurate and make it a fair test. There are not many health hazards in this experiment, so therefore, we do not need to wear any protective items, such as gloves or goggles, but we will still be very careful.

Results

Analysis

This experiment did not have a pattern, it depended on the structure of the sugars, using the Lock and Key Mechanism. If the sugar substrate managed to fit the enzyme active site properly, the yeast would then respire well. I have found out that the Sucrose worked the best, and the Sorbose worked the least best. I think that this is the case, because other groups may have done the tests more accurately than others. I do not see any patterns in my results. I made a prediction that the glucose would work the best. This was not the case. In actual fact, Sucrose worked the best. I know this, because if you look at the table, you will see that the Sucrose has the highest percentage change. Also, on the chart, the bar is the longest. There was no pattern in this experiment; It all depended on the structures of the sugar. In theory, Glucose should have been the sugar that worked the best, and lost the most amount of mass. I think that it did not because the experiment may have been tampered with, or changed in some way, to not produce accurate results. The results do not fit very well, as Galactose is supposed to be respiring a little bit, and it did not respire at all. There could have been a case where the balances were not working properly and gave different, inaccurate readings. There could have also been a case where the results could have been disturbed in some way, or the class maybe did not take the readings well. From this topic, I have learned that only a few sugars actually fit the active site of the yeast, and those are the sugars that totally metabolise, and let the yeast respire.

Evaluation

This experiment appeared to be very ineffective and very inaccurate, as the results we managed to obtain were not very reliable. The most inaccurate parts of this experiment were the results, as they were not very reliable. The reason for this was that different people amongst the class took the results, therefore increasing the chance of inaccuracy. If there was any part of the method to change, it would be the fact that the whole class took readings of different sugars and then combined the results. In my eyes, this is very inaccurate, and it would be better if the whole class took separate readings of all the sugars. Glucose was the most inaccurate result, as, in theory, it should be the sugar that would metabolise the quickest. However, in this experiment, it was Sucrose. One explanation to this, is that Sucrose is made up of two different sugars, one part being Glucose, therefore, it fits the lock and key mechanism well, therefore metabolising the most. My conclusion regarding this experiment is that it did not go very well, and it should have been Glucose that fitted the Sugar, using the Lock and Key theory. This is because it is an exact fit, and therefore, the Glucose substrate totally metabolises inside the yeast active site. I believe that repeating the experiment again would be a good idea, as the results of this experiment are unreliable.