Name ______Period ______

Accelerated Biology

Elodea Water Simulation

Objective: To observe how different variables affect the rate of photosynthesis in an aquatic plant.

Go to the following site: http://www.saddleworth.oldham.sch.uk/science/simulations/waterweed.htm

Procedure: There are many variables that you can use to get information from this simulation. It is very important that when you are testing a given variable, that it is the only variable that is changed.

For a trial run, set the CO2 and light level to 5.0. Click on the start button and watch the number of bubbles that appear. After counting the bubbles for 30 seconds, it will record them on the chart.

Notice that you can run this experiment in “real time” or “fast time.” You may want to do it in fast time.

Use the simulator to complete the data table below.

Practice Trials / CO2 / Light / Light Color / # of Bubbles
1 / 5 / 5 / Colorless
2 / 5 / 2 / Colorless
3 / 5 / 7 / Colorless
4 / 5 / 8 / Colorless
5 / 5 / 10 / Colorless
6 / 2 / 5 / Colorless
7 / 7 / 5 / Colorless
8 / 8 / 5 / Colorless
9 / 10 / 5 / Colorless

When you have completed the 9 practice trials, you can then choose an experimental variable to test: the CO2, light, or light filter. The goal is to produce the maximum bubbles possible, by changing only ONE variable.

Directions: Develop an experiment to test how the level of CO2, light, or light filter affects the rate of photosynthesis. Fill out the information below and construct a data table (conduct 20 trials) on the backside of the sheet that shows the data you collected. Make sure to include information such as the color of light, light intensity, level of CO2 and the amount of bubbles produced. Use the previous experimental data table as a guide.

Hypothesis (if . . . then):

Experimental Variable:

Dependent Variable:

Constants:

Data Table:

The Effect of ______on ______

Analysis: Type up your answers to the following questions.

1.  How does color affect the rate of photosynthesis?

2.  How does light intensity (light level) affect the rate of photosynthesis?

3.  How does the amount of CO2 present affect the rate of photosynthesis?

4.  What are the bubbles you are measuring in this lab? (Think about the photosynthesis equation) How can the bubbles tell you how fast photosynthesis is occurring?

5.  Why is it important that you keep two variables constant (such as light level and color) while you are testing how a third variable (CO2 level) affects photosynthesis?

6.  What settings did you put the simulator on to get the maximum rate of photosynthesis?

7.  Graph your data. Then, write a conclusion stating how your data/graph supports or refutes your hypothesis. Provide quantitative data to support your conclusion.