In This Chapter


Authored by: Luca Palmeri , Alberto Barauesse , Sven Erik Jørgensen

Ecological Processes Handbook

Print publication date:  August  2013
Online publication date:  August  2013

Print ISBN: 9781466558472
eBook ISBN: 9781466558489
Adobe ISBN:


 Download Chapter



Photosynthesis is the production of organic molecules (synthesis) based on carbon dioxide, water, and sunlight’s energy (photo is the Greek word for light), which is performed by plants, algae, and some bacteria, such as cyanobacteria and green–purple sulfur-oxidizing bacteria. Photosynthetic organisms, termed photoautotrophs because they can capture light and use it to fix the inorganic carbon from CO2 into high-energy organic compounds stored in their bodies (autotroph means self-feeding), are fundamental in ecology because they represent the energetic and carbon basis of all ecosystems. No other organism can synthesize organic carbon compounds based on inorganic carbon, with the exception of chemoautotrophs using chemical reactions as a source of energy instead of light, such as bacteria living nearly thermal vents under the sea (whose global productivity is however negligible). Therefore, predation upon photoautotrophs and the consequent incorporation of organic carbon in the predator tissues are the ways by which newly synthesized organic carbon from CO2 can enter the food web. Similarly, photosynthetic organisms represent the ultimate source of energy for ecosystems, since they can fix the energy coming from the sun, that is, outside of the earth. Most of biological productions on the earth can be traced back by means of predator–prey interactions to the energy and carbon fixed during photosynthesis and hence to the sun’s energy (see Chapter 15; notice that also the so-called photoheterotroph organisms use sunlight as a source of energy, but they use organic and not inorganic carbon as their carbon source).

Search for more...
Back to top

Use of cookies on this website

We are using cookies to provide statistics that help us give you the best experience of our site. You can find out more in our Privacy Policy. By continuing to use the site you are agreeing to our use of cookies.