Do different coloured wavelengths of light affect the rate of photosynthesis in Canadian Pond Weed?

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Do different coloured wavelengths of light affect the rate of photosynthesis in Canadian Pond Weed?

Aim;

For the aim of this experiment I am trying to discover if different coloured wavelengths of light affect the speed of photosynthesis in Canadian pond weed either speeding up the rate of photosynthesis or prolonging its effects, or even in some places stopping it take place completely.

Prediction;

I predict that the different wavelengths of coloured light will affect the rate of photosynthesis, for example I believe that when there is a green filter on the light there will be a very slow rate of photosynthesis, almost no reaction at all because pond weed is green and so this shows me that pond weed does not absorb green light it refracts it yet absorbs all the other coloured wavelengths.  I also believe that photosynthesis will not occur very fast with a similar colour to green such as yellow as these are next to each other in the colour spectrum. I believe that photosynthesis will react much faster with colours at the end of the spectrum such as red and blue as they are the two extremes of the colour spectrum, infrared and ultra violet.  As these two coloured wavelengths are the furthest away from the green wavelength I believe they will increase the rate of photosynthesis in the pondweed.  The light wavelength diagram shown below emphasises that infrared and ultra violet are the two coloured wavelengths of light furthest away from the green coloured wavelength.  I also believe that another aspect which will affect the results I achieve will be the temperature at which the experiment takes place.  

As the reaction photosynthesis uses enzymes to take place temperature is a key aspect in the experiment.  Enzymes are only active at certain temperatures.  If the temperature at which the experiment is to low say 20oC than the reaction will be slowed down as the enzymes will be inactive.  Also if the temperature is too high for example it is over 40oC the reaction time will also be slowed down as the enzymes will be inactive.  Enzymes are most active at around body temperature, 37oC and so temperature plays a key role.  Another reason why temperature will play a key role in the experiment is due to the collision theory.  As when particles are warmer they carry more energy and so collide more often causing more reactions to take place over a smaller period of time.  As I have no means to control the temperature at which the experiment will be taking place I predict that my results will be inaccurate.  With secondary colours I believe that the rate of photosynthesis will decrease due to the fact that secondary coloured wavelengths of light are closer to the green wavelength than infrared and ultraviolet wavelengths.  

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Fair Testing;

These are things I am going to keep the same;

  • The amount of sodium carbonate (1 spatula full)
  • The amount of water (500ml)
  • The same sized piece of pond weed ( 6cm)
  • The same amount of light (1 Lamp)
  • The same amount of timed intervals ( Every 30sec for 3min)
  • The temperature of the water (Room Temperature 23oC)

The thing that I changed was;

  • The colour of the filter ( 4 filters Red, Blue, Green, Clear)

Something’s had to remain the same such as the amount of light and the amount ...

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