What Is the Primary Role of Photosynthesis?

Photosynthesis generates sugar molecules from water, carbon dioxide, and sunlight. In many ecosystems, photosynthesis is the mechanism for primary producers to create the nutrients and energy transported to other living parts of the ecosystem.

Reaction for Photosynthesis

In photosynthesis, six water molecules and six carbon dioxide molecules in the presence of light yield one sugar molecule and six oxygen molecules.

Stages of Photosynthesis

Photosynthesis is often divided into two stages, the light reactions and the dark reactions corresponding to the role light plays in each stage.

Light Reactions

In the light reactions, photosynthetic pigments utilize light to energize electrons, which then allow the synthesis of high energy molecules to fuel the dark reactions. This process is often termed photophosphorylation.

Dark Reactions

In the dark reactions, carbon dioxide is "fixed" to produce glucose. This cycle requires the input of carbon dioxide from the environment and energy supplied by the energy molecules created in the light reactions. The process of carbon fixation is called the Calvin Cycle.

Photosynthetic Organisms

Plants are among the most recognizable photosynthetic organisms, but many protists (such as algae and dinoflagellates) and bacteria (for example, cyanobacteria) also carry out photosynthesis.

References

• Photosynthesis