Re: How can I show how wavelengths affect photosynthesis?

it seems that the most straight forward way to approach this experiment 
would be to expose the organisms to different wavelengths of light and 
monitor growth.  this would allow you to see which wavelength allows 
optimal growth.  there is much literature on the pigments directly involved 
in photochemistry and light harvesting which are the very first steps in 
photosynthesis.  there is also much literature on the wavelengths that 
agricultural plants use.  it has been shown that blue and red light are 
most often used.  it will also depend on the organism of interest.  algae 
and bacteria will layer at different depths in water and may develop 
different pigments to ensure survival.  ok....back to the experiment.  you 
can buy full spectrum light bulbs from the store and some filters (the 
plastic that 3-d glasses are made from).  depending on the number of 
different wavelengths you may need to buy the filters from an optics 
catalog (although this will be very expensive).  this is a primitive 
experiment, but there are alot of things that you will need to worry about. 
 you will have to make sure that the light each box recieves is equal and 
that temperature and CO2 levels are constant.  you will have to run most of 
these in duplicate and have controls without the filters.  another 
inconvienence is the lenght of time it will take to complete this 
experiment.  if you are working with plants and not algae or bacteria then 
you may be in for the long haul.  there are many other ways to run 
experiments like this but they involve expensive fluorimeters.  if you have 
access to an instrument like this then contact me and i will help you with 
a much easier and less time consuming experiment.