Date ______
Light Reaction Web Activity
Name _______________
Introduction:
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. This
simulator addresses three factors that influence the rate of
photosynthesis. Carbon dioxide availability, light intensity, and light
color can all be adjusted in the simulator to determine how each of the
factors affects the rate of photosynthesis.
Site: http://www.saddleworth.oldham.sch.uk/science/simulations/waterweed.htm
Directions: Using the tables below, set up an experiment to find the
answer to the question.
1. You must have at least 4 runs for each experiment.
2. Make sure that you click X5 speed
3. Remember you should only have a single variable in each experiment.
Pre-Lab Questions
_____________________
___________________________________________________________________
1. In this investigation, how will you measure the rate of photosynthesis?
____________________________
___________________________________________________________________
2. Why would this procedure not work with a terrestrial plant?
Question 1: How does the color of light affect the rate of photosynthesis?
 Hypothesis: ______________________________________________________________
______________________________________________________________________
Run
CO2
Data Table 1
Light
Filter
Count
Run 1
Run 2
Run 3
Run 4

_________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
Conclusions (Summarize the results of your experiment):
Date ______
Light Reaction Web Activity
Name _______________
Question 2: How does the light level (intensity) affect the rate of photosynthesis?
 Hypothesis: ______________________________________________________________
______________________________________________________________________
Run
CO2
Data Table 2
Light
Filter
Count
Run 1
Run 2
Run 3
Run 4

_________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
Conclusions (Summarize the results of your experiment):
The Light Reaction on a Molecular Level
Site: http://www.mhhe.com/biosci/genbio/biolink/j_explorations/ch09expl.htm
Directions: Click “Skip Intro” to use the simulation and answer the questions.
1. In the diagram on the right label
the following:
o
o
o
o
o
o
Photosystem I
Photosystem II
Electron Transport Chain
ATP Synthase
Stroma
Thylakoid Space / Lumen
2. Use the simulation to complete tables 1 and 2.
Date ______
Light Reaction Web Activity
Name _______________
Table 1: The effects of wavelength on rate of
light reaction
Table 2: The effects of the light intensity on
rate of light reaction
To complete the table set the light intensity at
100 lux and adjust the wavelength to the values
on the table.
To complete the table set the wavelength
at 650 nm and adjust the light intensity to
the values on the table.
Wave Length
(nm)
Approximate
color of light
% Maximal
ATP
Light Intensity
(lux)
400
0
450
40
500
80
550
120
600
160
650
200
% Maximal
ATP
1.
700
750
2.
3. Use the information from table 2 to predict the % maximal ATP at a light intensity of 220 lux.
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4. What combination of light intensity and wavelength is necessary to reach 100% maximal ATP?
______________________________________________________________________
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5. What two energy-storing molecules are produced by this process?
______________________________________________________________________
6. Explain what happens to the water molecules at photosystem 1.
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