How Does The Concentration Affect The Rate Of Respiration In Yeast

The graph shows that the respiration rate does increase as the yeast concentration rises, but levels off and eventually reached its saturation point, or decline, which occurs at 8.5g. This decline may occur because there are too many yeast molecules in comparison to the glucose, which may lead to yeast cells hindering a collision thus lessening the reaction.
The respiration rate increases as more yeast is added because it gives more opportunities for molecular collisions and so the amount of successful collisions increases and results in a higher respiration rate. The reaction then levels out and begins to reduce, this may happen because there are too many yeast cells and they are actually preventing successful collisions and, in a way, ‘suffocating’ each other, or it may be that there is simply not enough glucose for the yeast cells to feed off of anymore.
Anomalies occurred at 4.5g, 7.5, and 8.5, as shown in the appendices and table above, 4.5g jumps from 240ml to 150ml, 7.5g jumps from 188 to 240, and 8.5g from 170 to 220, this could be from multiple reasons such as equipment malfunction, uncontrollable variables such as temperature, or a human error when measuring out the yeast, glucose, or water.
Due to these anomalies the results for these tests may not show an accurate representation of the respiration rate, but with the mean having been calculated these anomalies are not as substantial.
There were many errors made while conducting this experiment. Firstly, in the preliminary glucose experiment out class conducted we used both glucose and sucrose which made the results contaminated. Secondly, the setup we used was not infallible, some of the cylinders we used to measure the CO2 released were not big enough to hold all of the gas and so toppled over while we were not in the
room.
In conclusion, by observing these trends and analysing the information it has been found that 7.5g of yeast is optimum with 1g of glucose, and that if you over-power the glucose with too much yeast it will result in a reduced respiration rate as seen at 9.5g when it begins to decline. The results do correlate with the hypothesis, but the drop off was unexpected, as I had simply expected the amount of CO2 to continuously raise. If we were to conduct this experiment again it would be beneficial to try more varied concentrations of yeast and to go up in smaller increments, as well as to use different types of yeast to see how this would affect the respiration process.