Diffusion and Passive Transport

Vocabulary flashcards covering diffusion, concentration gradients, facilitated diffusion, osmosis, and cellular behaviors in hypertonic, hypotonic, and isotonic solutions.

Diffusion

The slow, natural movement of molecules in a fluid from an area of high concentration to an area of low concentration without requiring energy.

Passive Transport

The movement of substances across a cell membrane that does not require cellular energy in the form of ATP, including diffusion, facilitated diffusion, and osmosis.

Concentration Gradient

A difference in the concentration of a substance from one area to another, down which molecules naturally move during diffusion.

Dynamic Equilibrium

A state reached at the end of diffusion where equal amounts of molecules move across a semipermeable membrane in each direction, resulting in no net change.

Facilitated Diffusion

The movement of large or charged molecules (such as glucose and ions) from high concentration to low concentration using a membrane transport protein without requiring energy.

Osmosis

The passive transport of water molecules across a semipermeable membrane from an area of low solute concentration to an area of high solute concentration (or from high water concentration to low water concentration).

Aquaporin

A specialized membrane protein that water molecules pass through to speed up movement across the cell membrane.

Hypertonic Solution

A solution that has a higher concentration of solute outside of the cell compared to the inside, causing water to leave the cell and the cell to shrink.

Hypotonic Solution

A solution that has a lower concentration of solute outside of the cell compared to the inside, causing water to enter the cell.

Isotonic Solution

A solution that has the same solute concentration as the inside of the cell, where water enters and leaves at equal rates to maintain cell shape in dynamic equilibrium.

Lysis

The swelling and bursting of an animal cell caused by excessive water intake when placed in a hypotonic solution like distilled water ($0\%$ solute).

Turgid

The swollen, stiff state of a plant cell that occurs when placed in a hypotonic solution, where water entry creates internal pressure against the cell wall while retaining its general shape.

Plasmolysis

The process occurring in a plant cell placed in a hypertonic concentrated salt solution, where water leaves, causing the cell body to shrink and pull away from the cell wall.