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Leaf Structure

A leaf may be viewed as a solar collector filled with photosynthetic cells. Plants are the only photosynthetic organisms to have leaves, although not all plants have leaves.

The raw materials of photosynthesis, water and carbon dioxide, enter the cells of the leaf. Oxygen, a by-product of photosynthesis, and water vapor exit the leaf.

In most land plants, water enters the roots and is transported up to the leaves through specialized cells known as xylem (pronounced zigh-lem). Plants have a waxy cuticle on their leaves to prevent desiccation, or drying out. Carbon dioxide and oxygen cannot pass through the cuticle, but move in and out of leaves through openings called stomata (stoma = "hole"). Guard cells control the opening and closing of stomata. When stomata are open to allow gases to cross the leaf surface, the plant loses water vapor to the atmosphere.

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Overview | Food Web | Leaf Structure | The Chloroplast | Pigments | Oxygen

Light Dependent Process | Light Independent Process

Problem Set

The Biology Project > Biochemistry > Introduction to Photosynthesis >