Experimento Fotosintesis

Biology Practical Work:
Photosynthesis:Colour and voltage.




Candidate number: 001177-006



Candidate: Florencia Cascante



School: Northern International School.November 2008
Practical Work

Photosynthesis: Colour and voltage.




Planning A:

Research Question:
In what ways does the combination of red LIGHT at different voltages andwhite Light at different voltages affect the rate of photosynthesis?

Hypothesis:

Prediction:
If I compare the rate of photosynthesis in Elodea (aquatic plant) at different lightbulb voltages and in colour red against the same different voltages and white light, I expect that photosynthesis rate would be higher with the highest voltage and white light.

TheoreticalBackground:

“The action spectrum of photosynthesis:
A spectrum is a range of wavelengths of electromagnetic radiation. The spectrum of light is the range of wavelengths from 400nm to 700nm. Eachwavelength is a pure colour of light:
400-525 violet - blue
525-625 green - yellow
625-700 orange - red

The efficiency of photosynthesis is not the same in all wavelengths of light. The efficiencyis the percentage of light of a wavelength that is used in photosynthesis.

The absorption spectra of photosynthetic pigments
The action spectrum of photosynthesis is explained by considering thelight absorbing properties of the photosynthetic pigments.
Most pigments absorb some wavelengths better than others:
• The greatest absorption is in the violet-blue range.
• There isalso a higher level of absorption in the red range of the spectrum.
• There is least absorption in the yellow – green range of the spectrum; most of its light is reflected.
There are somedifferences between the action spectrum and the absorption spectra. Whereas little light is absorbed by chlorophyll in the green to yellow range there is some photosynthesis. This is due to accessory...