Photosynthesis Oxygen Activity

Bubbles Released At Various Lengths Over Time 

	1st 30 sec	2nd 30 sec	3rd 30 sec	Mean # of  Bubbles
Directly	29	28	27	28
6 in. away	20	20	19	19.6
12 in. away	13	12	13	12.6
36 in. away	8	7	7	7.3
No light	5	3	4	4

The independent variable in this experiment is the distance of the plant from the light while the dependent variable in this experiment is the number of bubbles released at any given distance. The control variable in this experiment is the number of bubbles released when the lamp was shut off. 

In my graph, the pattern shown is that the further the graduated cylinder got from the lamp, the fewer the bubbles produced over a thirty second time frame. Another pattern I began to notice is that the number of bubbles produced in the first thirty second trial tended to be greater than the number of bubbles produced in the third thirty second trial. 

The number of bubbles produced (the dependent variable) changes based on how close the plant in the graduated cylinder is to the light (the independent variable.) The amount of bubbles produced when there is no light from the lamp reaching the plant (the control variable) sets the basis for bubbles produced over a time period exposed to no/little direct lighting.

Because photosynthesis uses light to complete the process, it makes sense that the fewer bubbles released happened farther away from light exposure. We were slowly removing light; therefore, we were slowing the photosynthesis process every time we moved the plant further from the light slowing the rate of oxygen leaving the plant. 

The pattern shown in the graph does correlate with what I expected to happen. 

I feel as though one way we could have made this experiment more reliable is by performing the experiment in a darker room. If we had performed the experiment in a darker room, the direct lighting of the classroom would not have had an affect on the amount of bubbles released in any of the trials. The bubbles also were not the same size, meaning we didn't necessarily have a standard bubble size, we simply just counted all bubbles released. You may be able to measure the volume of gas being released by catching it in some sort of balloon (or something similar) and calculate the volume from there. 

I predict that the number of bubbles would increase if you increased the power of the light bulb. 

(I apologize for the alignment of my data table; Blogger would not allow me to copy the table perfectly. The chart was also complicated to copy and paste, and Blogger would not allow me to attach the cropped version of the chart.)