The Effects of Light Intensity and Wavelength on
the Rate of Photosynthesis
Overview of Reaction
In this simulation, you will be manipulating two variables: light intensity and light wavelength. The
amount of ATP produced will change depending upon the set parameters. Go to "Johnson
Explorations: Photosynthesis" located at
http://www.mhhe.com/biosci/genbio/biolink/j_explorations/ch09expl.htm . Look over the diagram
before clicking on "skip intro" so you have a fair idea what is going on, the above diagram will
also help.
Procedure: Your task is to use the simulation to determine how wavelength and intensity affect
the rate of photosynthesis (and the production of ATP). Keep in mind you are dealing with two
variables, so in order to determine absolutely how each factor affects photosynthesis, you must
keep one variable constant while manipulating the other variable.
Lab Report must contain the following typed sections.
1. Introduction: Describe briefly the light dependent reactions and propose a hypothesis to
answer the experimental question.
2. Data: Include data tables for the simulation. The tables must show clearly trends resulting from
changes of intensity and changes of wavelength. Multiple data tables would probably be best
here. In Microsoft Word, use the "table" function to organize your data.
3. A graph showing how the percentage of ATP changed (Y axis) as a result of changes in
wavelength and intensity (X axis). Two graphs would be best here. You may use Create A Graph
to make your graphs, or use a spreadsheet or graphing program of your choice.
3. Conclusion: Use your data to answer the experimental question. Answer clearly how light
wavelength affects the reaction, and how light intensity affects the reactions. Offer an explanation
of the results, taking into account the principles of photosynthesis and the light reaction.