# Plotting glucose production against time , x-axis & y-axis issue

Working on a pre-lab, some of the directions for drawing graphs is that the "x-axis" is for the non-variables, and the "y-axis" is for the variables (what you have measured).

Now, the first thing I have to do is to make a standard curve for "Glucose concentration" and "Absorbtion".

The next step is to measure the "Enzyme activity" and use the standard curve done to deternmine the amount of glucose since I will be having the "Absorbance" values in the "Enzyme activity" process.

Finally, we are asked to plot a graph that shows the glucose production against time.

Based on that, what (glucose production, time) goes where (x-axis, y-axis)?

Thanks.

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What is a "non-variable"? A constant? I think what you meant to say is that the "x-axis" is usually reserved for the independent variable, while the "y-axis" is reserved for the dependent variable. Time is an example of an independent variable. Wether you perform your experiment or not, it is still flowing, so to speak. On the other hand, all the variables you measure during your experiment will likely take on different values at different times, they therefore depend on time. –  Raskolnikov Feb 5 '11 at 16:44

But, isn't time a variable? And, thus has to go to the y-axis? –  Simplicity Feb 5 '11 at 15:08