Waterweed Simulation
Name:
Part 1: What factors affect the rate of photosynthesis?
Write down the balanced equation for photosynthesis. Label reactants and products.
Now, looking at the equation above, what relationship can you predict that exists
between the concentration of carbon dioxide and the rate of photosynthesis?
Photosynthesis literally means “light making”. Think about plants and where they grow
best, on the space below, make a statement regarding what relationship you believe
exists between the intensity of light and rate of photosynthesis.
Lastly, besides the amount of light, the quality of light also plays a role in photosynthesis.
We have discussed that white light is actually a combination of Red Orange, Yellow,
Green, Blue and Violet portions of the visible electromagnetic spectrum. On the line
below, hypothesize how you think the color (wavelength) of light affects the rate of
photosynthesis.
Part 2: Testing your hypotheses
In this lab we will be working with a virtual plant scenario. In this simulation, you will
have a plant that is kept in a controlled environment.
What does a controlled environment mean?
In this simulation, you will be looking at the production of oxygen as a plant (the
waterweed) photosynthesizes. Oxygen production is measured in the number of bubbles
produced by the plant. Three factors that influence the rate of photosynthesis can be
adjusted in the simulator to determine how each of the factors affects the rate of
photosynthesis.
Go to http://www.saddleworth.oldham.sch.uk/science/simulations/waterweed.htm
Effect of Light Color on the Rate of Photosynthesis
Set the simulator to 6.0 Light Level, and 6.0 CO2 Level. Adjust the colors to complete
the table.
Trial 1
Trial 2
Trial 3
Average
Light Color
Red
Blue
Green
Colorless
(white)
1. Based on the data, what color of light results in the fastest rate of photosynthesis?
2. Using the graph paper provided, create a graph which displays your results. WHAT
KIND OF GRAPH IS APPROPRIATE FOR THIS KIND OF DATA? Be sure to
consult your graphing checklist!
Effect of Light Level on Photosynthesis
Set the simulator to colorless light and CO2 level to 6.0. Make adjustments to the level of
light to complete the data table.
Trial 1
Trial 2
Trial 3
Trial 4
Light Level
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
1. Based on the data, what intensity of light results in the fastest rate of
photosynthesis?
2. Again, construct a graph to display your results. Is it appropriate to use the same
kind of graph that you did for part I?
Effect of CO2 Level on Photosynthesis
Set the simulator to colorless light and to 6.0 light level. Adjust the CO2 levels to
complete the table.
Data Table
CO2 level
Trial 1
Trial 2
Trial 3
Average
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
1. Based on the data, what level of CO2 results in the fastest rate of photosynthesis?
2. Again, construct a graph to display your results.
Analysis Questions
Name _____________________________
1.
Why is it important that you keep two variables constant (such as light level
and color) while you're testing how a third variable (CO2 Level) affects
photosynthesis?
2.
What settings can you put the simulator on to get the MAXIMUM rate of
photosynthesis?
3.
Sometimes, at a certain point, variables reach a “saturation point” at which
increasing one variable no longer leads to an increase in the other variable.
Explain what this means with regards to question number 2.
4.
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 plants’ photosynthetic activity and justify your answer!