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Photosynthesis

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Photosynthesis is the process associated with green chlorophyll that converts electromagnetic energy into chemical energy that becomes food for all living organisms. The blue and red light are the primary energy sources that drive the photosynthetic process, which typically on land, occurs in leaves, the solar collectors for photosynthesis.

Below are two sections of resources. The first set provides detailed illustrations and information about photosynthesis. The second set are resources on how plants use light in addition to photosynthesis (photobiology).

Why two sections? Light interacts with all objects in three possible ways: it may be absorbed, reflected, or transmitted through the object. Most of the remote sensing techniques of vegetation currently in use monitor the proportions of different wavelengths of light reflected by leaves.

The amount of light reflected by leaves depends on how much is absorbed by and transmitted through them, so we need to understand the processes that influence absorbtion and transmission of light by leaves. Much of the light absorbed by leaves is used for photosynthesis, and plants respond to competition by sensing the proportions of light transmitted through and reflected by neighboring plants.

Go to Plant Investigations

Go to Plant Stress Detection Glasses to see the health of plants

Light hitting a plant can either be transmitted, absorbed, or reflected. Typically plants absorb: 15% of Near IR, 82% of red, 80% of green, and 84% of blue. They reflect: 53% of near IR, 10% of red, 13% of green, and 9% of blue. They transmit: 32% of near IR, 8% of red, 7% of green, and 7% of blue.

Notice: % Reflected + % Transmitted + % Absorbed = 100%

Internet Resources on Photosynthesis

BioBook, created by Dr. Mike Farabee from Estrella Mountain Community College, Avondale, Arizona, is well illustrated, detailed, yet concisely written information about photosynthesis.

Photosynthesis Hypertextbook from Massachusetts Institute of Technology contains details information and illustrations of the chemical processes occurring during photosynthesis.

University of Cincinnati Clermont College website on photosynthesis.

Descriptions with recommendation of age ability of photosynthesis links from Arizona State University's Center for the Study of Early Events in Photosynthesis.

Video segment from Interactive NOVA: "Earth"  (2:30) takes the viewer from the earliest scientific hypotheses that plants ate dirt, to our present-day understanding of photosynthesis.

Books on Photosynthesis

A well-illustrated and clearly written book about the many processes of life is The Way Life Works by Hoagland and Dodson, 1998, published by Three Rivers Press.

A technical book, Photosynthesis, Sixth Edition by Hall and Rao, 1999, published by Cambridge University Press, has a fascinating second chapter describing the history of the discoveries of the photosynthetic processes.

Resources for Plants "Seeing" Light (Photobiology of Plants)

Operation: Colored Mulch, created by Ali Smith for the Agricultural Research Service of the U.S. Department of Agriculture (middle school activities).

How Plants See, September, 2004 issue of Natural History. The link contains only the text of the article. Illustrations are available in the print version of the magazine.

Plant Photobiology Notes with many resources for selecting equipment for light experiments with plants.

American Society for Photobiology has materials for students.

See Plant and Soil Sciences eLibrary for more in-depth material on plants and soils.