Name _______________________________________
In this lab we will be working with a virtual plant scenario. In this simulation, you will have a elodea plant that is kept in a controlled environment.
What does a controlled environment mean?
Procedure and Data
In this simulation, you will be looking at the production of oxygen as a plant (the waterweed elodea) photosynthesizes. Oxygen production is measured in the number of bubbles produced by the plant
(dependent variable). Three factors that influence the rate of photosynthesis can be adjusted in the simulator to determine how each of the factors (independent variables) affects the rate of photosynthesis.
Go to http://www.saddleworth.oldham.sch.uk/science/simulations/waterweed.htm
Set the simulator to Light Level 6.0, and CO
2
Level 6.0. Adjust the colors to complete the table. For each color, press “start” to let the experiment run for 30 seconds; the numbers of bubbles produced in each trial will be automatically collected and displayed in the data table. Repeat for 5 trials and record your data. Change to the next color and repeat until you have tested each of the colors of light and white.
Trial 3 Trial 4 Trial 5 Avg.
Light Color
Trial 1
Red
Blue
Green
Colorless
(white)
Trial 2

1.
Graph your data (average rate!). Remember to give your graph a title and label the axes.
2.
Based on the data, what color of light results in the fastest rate of photosynthesis?

1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
Set the simulator to colorless light and CO
2
level to 6.0. Make adjustments to the level of light to complete the data table as before.
Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Average
Light Level

1.
Graph your data (average rate!). Remember to give your graph a title and label the axes.
2.
Based on your data, is there an optimum light intensity for driving photosynthesis? If so, what is it?
3.
Describe the general relationship between light intensity and photosynthetic rate.

2
Keep the light set at colorless and set the light level to 6. Adjust the CO
2
levels to complete the data table below.
Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Average
CO
2
level
2.0
4.0
6.0
8.0
10.0
1.
Graph your data (average rate!). Remember to give your graph a title and label the axes.

2.
Based on the data, what level of CO
2
results in the fastest rate of photosynthesis?
3.
Describe the general relationship between CO
2
concentration and photosynthetic rate.
ANALYSIS
In this experiment, we observed how three different factors affect the rates of photosynthesis. Thinking about past discussion on chemical reaction rates, how can heat play a role in photosynthetic rates? Make a prediction on how heat would affect the rates of photosynthesis and justify your answer!
Why is it important that you keep two variables constant (such as light level and color) while you're testing how a third variable (CO
2
Level) affects photosynthesis?
Based on your data, what settings would you put the simulator on to get the MAXIMUM rate of photosynthesis?

In our previous unit on enzymes, we observed that at a certain point enzymes reach what is called a
“saturation point”. Did you observe a saturation point with either light intensity or CO
2
concentration?
We all know that plants are predominantly green in color (at least the parts that photosynthesize). If a plant were placed in a room that lacked the green wavelengths of the electromagnetic spectrum, predict what would happen to the plant’s photosynthetic activity and justify your answer!