Photosyntetic Pigments Essay Sample

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A photosynthetic pigment or antenna pigment is a pigment that is present in chloroplasts or photosynthetic bacteria and captures the light energy necessary for photosynthesis.  Chlorophyll a is the most common of the six, present in every plant that performs photosynthesis. The reason that there are so many pigments is that each absorbs light more efficiently in a different part of the spectrum. Chlorophyll a absorbs well at a wavelength of about 400-450 nm and at 650-700 nm; chlorophyll b at 450-500 nm and at 600-650 nm. Xanthophyll absorbs well at 400-530 nm. However, none of the pigments absorbs well in the green-yellow region, which is responsible for the abundant green we see in nature.

Green plants have six closely-related photosynthetic pigments (in order of increasing polarity):

* Carotene – an orange pigment

* Xanthophyll – a yellow pigment

* Chlorophyll a – a blue-green pigment

* Chlorophyll b – a yellow-green pigment

* Phaeophytin a – a gray-brown pigment

* Phaeophytin b – a yellow-brown pigment

Electromagnetic Spectrum

Light behaves as if it were composed of “units” or “packets” of energy that travel in waves. These packets are photons.

The wavelength of light determines its color. For example, The wavelength of red is about 700 nm and the wavelength of blue light is about 470 nm.

Graph.1: Made by Raffaela Pastore Meneguetti

Visible light is a part of a larger spectrum of radiation called the electromagnetic spectrum.

Image 1: Source

Photosynthetic Pigments

Pigments are molecules that absorb light. When a photon of light strikes a photosynthetic pigment, an electron in an atom contained within the molecule becomes excited. Energized electrons move further from the nucleus of the atom.


Find different results for any colored tube and cellophane involving the Geranium plants.


I believe that each color will act and will have different results at the plant (like growth and coloration).


First of all we divided our class in 4 groups, each group must work in a Laboratory referent to something with Photosynthesis. My group kept a experience related to the Photosynthetic Pigment. With it we try to show that which solar radiation have a different reaction at our plant.

To do it we needed:

* 4 Colors of Cardboard (Red, Blue, Yellow, Black)

* 4 Colors of Cellophane (Red, Blue, Yellow, Transparent with double layers)

* Crape Tape

* Supports

* Luminaries

* Scissors

* Pen

* Geranium

* Boards of Implement (Petri Dish)

* Ruler

* Thermometer

With the cardboard we made a tube, the colored side was turned into it. Inside of our tube we put a Petri dish and the Geranium inside of it, to close our tube we glue, with the Crape tape, the cellophane (at the same color of the cardboard and the transparent with the black one). We also made at the base 7 holes, so our Geranium could breath.

After one week, we took out the tube to see what happened with our plant, and like I presumed, the colored have interfered at the results.

Graph 2: Made by Raffaela Pastore Meneguetti

Like we can see at the graph the plant with the highest growth was the red, with the highest wavelength and the cellophane blue made de Geranium have a little decrease at its size (the blue wavelength is the lowest). The follow graph shows this parallel.


This was a interesting laboratory, but my group forgot to do some notes. For example we only measured the lamp and the environment temperature at the beginning, respectively 34� C and 28� C. We also made another mistake, we forgot to irrigate our plants and they get really dry this can be a reason why did the Geranium with the transparent cellophane not grew.

But if I can remade it I would make one more tube, a green one. Because only with the green photosynthetic pigment the plant cannot survive, the plant will not take their energy and this is also a important data.


All accessed at April 26, 2008














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