Diffusion

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Diffusion Noun

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[di-fyoo-zhun]

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Diffusion

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The net movement of particles from a region of higher concentration to a region of lower concentration down a gradient.

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Example: This diagram shows particles moving from an area of high concentration (left) to an area of low concentration (right) across a cell membrane over time.

Front

Kinetic Theory of Matter Noun

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[ki-net-ik thee-uh-ree ov mat-er]

Back

Kinetic Theory of Matter

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The scientific theory stating that all matter consists of many small particles that are in constant, random motion.

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Example: This diagram shows that all matter is made of moving particles. Particles in solids vibrate, while those in liquids and gases move more freely.

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Solute Noun

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[sol-yoot]

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Solute

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A substance that is dissolved in another substance, the solvent, to form a solution.

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Example: This image shows a solute as the particles (the white spheres) that are dissolved and spread evenly throughout a solvent (the blue liquid).

Front

Solvent Noun

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[sol-vent]

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Solvent

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The substance in which a solute dissolves to produce a homogeneous mixture known as a solution.

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Example: This image shows that a solvent, like water, is the substance in which another substance, the solute (sugar), dissolves to form a solution.

Front

Concentration Noun

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[kon-sen-tray-shun]

Back

Concentration

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The measure of the amount of a given substance, the solute, contained in a particular volume of solution.

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Example: This image shows several beakers with the same amount of liquid but different amounts of a purple substance, illustrating how concentration can vary from high to low.

Front

Concentration Gradient Noun

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[kon-sen-tray-shun gray-dee-ent]

Back

Concentration Gradient

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The gradual difference in the concentration of a substance between two areas, which drives particle movement.

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Example: Particles are crowded on one side (high concentration) and spread out on the other (low concentration). This difference across the space is the concentration gradient.

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Net Movement Noun

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[net moov-ment]

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Net Movement

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The overall directional movement of particles from an area of higher concentration to one of lower concentration.

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Example: This diagram shows that over time, particles naturally move from an area of high concentration (outside the cell) to an area of low concentration (inside).

Front

Equilibrium Noun

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[ee-kwi-lib-ree-um]

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Equilibrium

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The state where the concentration of a substance is uniform throughout a medium, resulting in no net movement.

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Example: This diagram shows a solution where solute particles are evenly distributed among solvent particles, representing the state of equilibrium achieved after diffusion is complete.

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Passive Transport Noun

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[pas-iv trans-port]

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Passive Transport

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The movement of substances across a biological membrane without the expenditure of cellular energy.

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Example: Molecules move from an area of high concentration (extracellular fluid) to low concentration (cytoplasm) directly across the cell membrane, without using energy.

Front

Surface Area to Volume Ratio Noun

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[sur-fis air-ee-uh too vol-yoom ray-shee-oh]

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Surface Area to Volume Ratio

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A ratio comparing the total surface area of an object to its volume, which decreases as a cell grows.

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Example: As a large cube is divided into smaller cubes, the total volume stays the same, but the total surface area increases, raising the SA:V ratio.