Name: __________________________________________ Date: ______________ Period: _______
Virtual Lab: Optimizing Photosynthesis
In this simulation, you will be looking at the production of oxygen as a plant photosynthesizes. This procedure
can be accomplished by placing elodea plants in water with baking soda to provide carbon. The plant can then
be exposed to varying intensities and colors of light. Oxygen is measured in the number of bubbles produced
by the plant. The diagram below is an online simulation of elodea in an apparatus where three environmental
conditions can be controlled. http://www.saddleworth.oldham.sch.uk/science/simulations/waterweed.htm
This simulation will be used to investigate the impact of these variables on the rate at which photosynthesis
occurs. The three variables are:
 Color of light shining on the plant
 Level (intensity) of light directed at the plant
 Level (amount) of CO2 in the air surrounding the plant
Review the diagram below, including the directions for controlling the three variables and determining whether
they will have an impact on the rate of photosynthesis.
Pre-Lab Questions: Answer the following questions based on your understanding of photosynthesis and the
information provided for the simulation.
1. Which two variables are controlled in a similar manner?
2. How can you get the results to the investigation faster?
3. How will you be able to determine the rate of photosynthesis in this simulation?
4. Write the chemical equation for photosynthesis.
5. What gas do bubbles that appear in the simulation represent?
6. Write a hypothesis for each of the controlled (or independent) variables in this simulation. Be certain to
include both a statement of what you would expect the impact to be for each variable on the rate of
photosynthesis (the number of bubbles appearing in a set period of time) AND the reason it would have this
impact.
a. color of light:
b. level (intensity) of light:
c. level (amount) of CO2:
7. Describe how you would investigate the impact of different CO2 levels on the rate of photosynthesis. Include
in your explanation any variables that would be kept constant and any that you would change.
Effect of Light Color on the Rate of Photosynthesis
LIGHT COLOR # of BUBBLES
Red
Blue
Green
Colorless
1. Using evidence from your investigation, 1) what effect did this factor have on photosynthesis and 2) which
color of light results in the fastest rate of photosynthesis and why?
Effect of Light Level on Photosynthesis
LIGHT LEVEL
# of BUBBLES
(Light = colorless / CO2 = 6.0)
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
2. Using evidence from your investigation, 1) what effect did this factor have on photosynthesis and 2) which
light level results in the fastest rate of photosynthesis and why?
Effect of CO2 Level on Photosynthesis
Develop an experiment to test how the level of CO2 affects the rate of photosynthesis. Construct a data table in
the space below 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 experiments as a guide).
Be sure to fill out the titles/labels in the chart below.
3. Using evidence from your investigation, 1) what effect did this factor have on photosynthesis and 2) which
CO2 level results in the fastest rate of photosynthesis and why?
Analysis Questions:
4. What settings can you put the simulator on to get the MAXIMUM rate of photosynthesis?
5. Why is it important that you keep 2 variables constant (such as light level and color) while you’re testing
how a third variable (CO2 level) affects photosynthesis?
6. cutting down a large number of trees in forested areas contribute to global climate change. What is one
reason that cutting down trees would increase the greenhouse effect?