Biology  5/e   Raven/Johnson
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Adhesion, cohesion, and capillary movement: When one substance clings (adheres) to another substance, this is called adhesion. When a substance clings to more of the same substance, this is called cohesion. Water adheres to surfaces and coheres to itself. In small diameter spaces, the adhesion to the surface pulls on the water. Because of the strong cohesive forces in water, the water responds to the pull as a unit instead of breaking away and sinking. This process by which water rises up small-diameter columns is called capillary action.

Osmosis: The diffusion of water down its own concentration gradient (from low-solute concentration to high-solute concentration gradient) through a differentially permeable membrane is called osmosis.

Transport of ions across membranes: Passages through the cell membrane are bound by proteins that recognize various substances and bind with them to allow passage to the inside. If a substance is to be transported up its concentration gradient instead of down, energy must be supplied at the expense of ATP.

Xylem and phloem: Xylem conducts water throughout vascular plants. Xylem elements include tracheids and vessel elements. Phloem conducts food throughout the vascular plant. Phloem is composed of sieve cells or sieve-tube elements and carries out the metabolic activity for the sieve-tube elements.

Endodermis: The endodermis is the innermost layer of the cortex. It regulates the passage of minerals and nutrients to and from vascular tissue.

Stomata: Stomata are openings in the epidermis through which gases pass. The opening is regulated by a pair of cells called guard cells.

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