Unit 3 Diffusion Osmosis Active Transport

study bio w me

Diffusion

The movement of molecules from a region of higher concentration to a region of lower concentration, down a concentration gradient.

Osmosis

The passage of water molecules from a region of higher water potential to a region of lower water potential, down the water potential gradient, through a partially permeable membrane.

Concentration gradient

The difference in concentration between two regions.

Turgor pressure

The pressure exerted by water inside the central vacuole against the cell wall of a plant cell, keeping it firm.

Plasmolysis

The shrinkage of a cell's cytoplasm away from the cell wall due to loss of water.

Crenation

The shriveling of an animal cell that occurs when it loses water in a hypertonic solution.

Active transport

The movement of ions from low concentration to high concentration, against the concentration gradient, requiring energy.

Factors affecting the rate of diffusion

Includes concentration gradient, temperature, and surface area to volume ratio.

Water potential

A measure of the tendency of water to move from one place to another.

Dilute solution

A solution that contains a relatively high concentration of water molecules compared to solute.

Kinetic energy

The energy possessed by particles due to their motion; affects the rate of diffusion.

Partially permeable membrane

A membrane that allows certain molecules or ions to pass through it by diffusion and occasionally by specialized processes.

Ion absorption

The process through which roots take in mineral ions from the soil against the concentration gradient.

Temperature effect on diffusion

Higher temperatures increase the kinetic energy of particles, leading to faster movement.

Surface area to volume ratio

A higher ratio increases the rate of diffusion due to more area available for particles to cross.

Respiration

The process of breaking down food substances to release energy, needed for active transport.