First, I would calculate the mean RATE of bubbling (if you have 2 min counts, that simply means div by 2) for each sugar.
The graph you are suggesting is MAD!!!
Y axis would be rate (as above)
X asis would be time intervals
BUT, BUT BUT I can see no point whatever in doing that!!
To repeat 00's of earlier posts, there are TWO factors here - getting into the cell and turning the sugar into a respiratory component.
From then on, all is the same, no matter what
Now, the longer you let the whole thing run, the longer the cell has to synthesise the necessary proteins to speed up BOTH rate-limiting steps.
In short, it will go faster and faster
As the expt goes on, the substrate is used up
thus, as time goes on, it goes slower and slower
TWO opposing events.
TWO explanations thus needed, thus attempting to explain why the methodology is fundamentally flawed (you need to ensure a constant, XS [substrate]; not possible in a school system.
Bya ll means witter on about the changes in the no of bubbles over time (it won't cost you marks) BUT, BUT BUT
The ONE thing you are attempting to show is a difference between the sugars which requires a bar chart with standard error bars.
Assuming your 6 time intervals were (basically) continuous (ie over about 30-90 mins in all), siply calculate the mean of the whole lot (= 18 readings?) turn into a mean RATE and then plot as above.