I recently did a lab in BIO class and tested chloryphyll extract in a spectrophotometer. Why is the absorbance of light vary according to wavelengths.I have to make a lab report and i don't know...

I recently did a lab in BIO class and tested chloryphyll extract in a spectrophotometer. Why is the absorbance of light vary according to wavelengths.

I have to make a lab report and i don't know how to discuss my results that I got.

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pacorz | High School Teacher | (Level 3) Educator

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Chlorophyll's function within plant cells is to absorb photons, or packets of light energy; the photons' energy is used to excite electrons, and then the excited electrons are brought back down to their normal energy states in a controlled manner, and the excitation energy is captured and used to make ATP for the plant. In order for this to work, the amount of energy in the photon needs to be closely matched to the electron to be excited.

Photosystem I uses chlorophyll a in a form know as P700. P This form of chlorophyll best absorbs light with a wavelength of 700 nanometers. Photosystem II uses a slightly different form of chlorophyll, P 680, which absorbs best at 680 nm. Many plants also use chlorophyll b and other accessory pigments. each of which absorbs different wavelengths. When you look at the different absorbance peaks in your spectroscopy data, you are seeing the collective absorbances of several different photosynthetic pigments all mixed together in the sample extract. For the plant, it is advantageous to  be able to use a wide range of different colors of light to do photosynthesis.

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