Photosynthesis | Biology

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Photosynthesis

Alternative Photosynthesis Pathways

In biology, photosynthesis is a process used by plants and other organisms to convert light energy, normally from the Sun, into chemical energy that can later be released to fuel the organisms' activities. In most cases, oxygen is also released as a waste product. Most plants, most algae, and cyanobacteria perform photosynthesis. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. It also occurs in some species of fungi. Photosynthesis is crucial for all aerobic life on Earth. In all photosynthetic organisms, some energy from sunlight is used to reduce carbon dioxide to sugar, either directly, or indirectly after making organic compounds. In all plants, algae, and cyanobacteria, this carbon fixation is performed by a sequence of enzyme-catalyzed reactions called the Calvin cycle, which reduces the CO to sugar, which is later converted to the simple carbohydrate starch or sucrose and to other products. In green plants, the products are cellulose and lignin, and in algae they are starch and glycerol.

Dennis Howard

Photosynthesis - Overview

The Light Reactions

Electron Flow

The Calvin Cycle

Photorespiration

Alternative Photosynthesis Pathways

Mitochondria vs. Chloroplasts

Life on Earth Depends on Photosynthesis