Notes - Wavelength Essay examples

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Not all wavelengths of light can support photosynthesis. The photosynthetic action spectrum depends on the type of accessory pigments present. For example, in green plants, the action spectrum resembles the absorption spectrum for chlorophylls and carotenoids with peaks for violet-blue and red light. In red algae, the action spectrum overlaps with the absorption spectrum of phycobilins for blue-green light, which allows these algae to grow in deeper waters that filter out the longer wavelengths used by green plants. The non-absorbed part of the light spectrum is what gives photosynthetic organisms their color (e.g. green plants, red algae, purple bacteria) and is the least effective for photosynthesis in the respective organisms.

http://www.botany.uwc.ac.za/ecotree/photosynthesis/spectrum.htm

Plants could use the ultraviolet or infrared section of the spectrum for photosynthesis but here is why they don't.
Ultraviolet light Each photon of ultraviolet electromagnetic radiation contains too much radiation for most biological systems. Its high energy drives electrons from molecules and breaks weak bonds. It is absorbed by oxygen in the forms O2 and O3 (ozone). The ozone layer of our atmosphere protects life on the planet from high levels of ultraviolet radiation.
Infrared light Each photon of infrared electromagnetic radiation does not contain enough energy to do useful work in a biological system. Cells do absorb this radiation but it contains insufficient energy to excite electrons of molecules and is thus converted to heat. Infrared radiation is absorbed by water and by carbon dioxide in the atmosphere.
Visible light Each photon of visible light contains just enough energy to excite the electrons of molecules without causing damage to the cel
Light quality refers to the color or wavelength reaching the plant surface. Sunlight can be broken up by a prism into respective colors of red, orange, yellow, green, blue, indigo, and violet. On a rainy day, raindrops act as tiny prisms and break the sunlight into these colors producing a rainbow. Red and blue light have the greatest effect on plant growth. Green light is least effective to plants as most plants reflect green light and absorb very little. It is this reflected light that makes them appear green. Blue light is primarily responsible for vegetative growth or leaf growth. Red light when combined with blue light, encourages flowering in plants. Fluorescent or cool-white light is high in the blue range of light quality and is used to encourage leafy growth. These lights are excellent for starting seedlings. Incandescent light is high in the red or orange range but generally produces too much heat to be a valuable light source. Fluorescent "grow" lights have a mixture of red and blue colors that attempts to imitate sunlight as closely as possible. They are costly and generally not of any greater value than regular fluorescent lights

http://ag.arizona.edu/pubs/garden/mg/botany/environmental.html
Photosynthesis: Process by which plants convert sunlight to useable energy

-During light reactions a photon’s energy is
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