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photosynthesis
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Diagram of a tree leaf illustrating photosynthesis, with arrows showing sunlight, water, and carbon dioxide entering the leaf and sugars and oxygen being produced. A person is shown beside the tree to demonstrate the exchange of oxygen and carbon dioxide between plants and animals.
Learn About the Greenness of Plants
Learn How the Layered Arrangement of Chlorophyll Molecules Within a Leaf Increases Its Photosynthetic Output
Colored scanning electron micrograph showing green, bead-like cyanobacteria filaments intertwined, with several round, spiky pink spores scattered among them. A diagram shows the process of photosynthesis, where carbon dioxide and water, using light energy and chlorophyll in leaves, are converted into glucose and oxygen. The chemical equation 6CO2 plus 6H2O yields C6H12O6 plus 6O2 is displayed.
How Does Photosynthesis Work?
The Relationship Between Photosynthesis and Breathing
Diagram of a chloroplast showing its structure, including the outer and inner membranes, stroma, thylakoids stacked into grana, stroma lamellae, lumen, and intermembrane space.
The Process of Photosynthesis in Plants Explained
Chlorophyll b
At a Glance
Photosynthesis diagram showing how water, light, and carbon dioxide are absorbed by a plant and that oxygen and sugars are produced. Also show a person to illustrate the oxygen/carbon dioxide cycle between plants and animals.
Pop Quiz: 13 Things to Know About Photosynthesis
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photosynthesis summary
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greylag. Flock of Greylag geese during their winter migration at Bosque del Apache National Refugee, New Mexico. greylag goose (Anser anser)
Biology Bonanza
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Written by
James Alan Bassham
Senior Scientist, Chemical Biodynamics Division, Lawrence Berkeley Laboratory, University of California, Berkeley, 1978–86; Research Chemist, 1949–77. Coauthor of Photosynthesis of Carbon Compounds;...
James Alan BasshamAll
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Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree....
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Diagram of a chloroplast showing its structure, including the outer and inner membranes, stroma, thylakoids stacked into grana, stroma lamellae, lumen, and intermembrane space.
Chloroplast structureThe internal (thylakoid) membrane vesicles are organized into stacks, which reside in a matrix known as the stroma. All the chlorophyll in the chloroplast is contained in the membranes of the thylakoid vesicles.

The process of photosynthesis in plants and green algae takes place entirely within the chloroplasts, a type of cell organelle. Chloroplasts are a type of plastid—a round, oval, or disk-shaped body that is involved in the synthesis and storage of foodstuffs. They are distinguished from other types of plastids by their green color, which results from the presence of two pigments, chlorophyll a and chlorophyll b. Some single-celled algae have one chloroplast that occupies more than half the cell volume. Leaf cells of higher plants contain many chloroplasts, each approximately the size of the one in some algal cells.