Diffusion and Osmosis

Vocabulary flashcards covering diffusion, osmosis, tonicity, and osmoregulation concepts from the notes.

Cell membrane

A semi-permeable boundary that controls what can enter or leave a cell.

Semi-permeable

A property of membranes that allows some substances to pass more easily than others, often based on size.

Dialysis tubing

A laboratory semi-permeable membrane used to study diffusion and osmosis.

Solvent

The liquid in a solution that dissolves a substance.

Solute

The substance dissolved in a solvent.

Concentration

The amount of solute in a solution, often expressed as a percentage.

Diffusion

Spontaneous movement of particles from high concentration to low concentration, tending toward even distribution.

Concentration gradient

The difference in solute concentration across a membrane; steeper gradients speed diffusion.

Kinetic energy

Energy of motion that drives diffusion; higher temperatures increase molecular motion.

Entropy

A measure of disorder; diffusion tends toward greater entropy.

Second Law of Thermodynamics

Tends to drive systems toward increased entropy and more disorder.

Osmosis

Diffusion of water across a semi-permeable membrane from low solute concentration to high solute concentration.

Hypertonic

Environment with higher solute concentration than the cell; water tends to leave the cell.

Hypotonic

Environment with lower solute concentration than the cell; water tends to enter the cell.

Isotonic

Environment with solute concentration equal to that inside the cell; balanced water movement.

Turgor pressure

Pressure from water inside a plant cell’s central vacuole pressing the membrane against the cell wall, providing structural support.

Central vacuole

Large, water-filled organelle in plant cells that maintains turgor pressure.

Osmoregulation

Regulation of water and solute balance in organisms.

Marine fish

Saltwater fish that drink water to maintain salt balance and excrete excess salts; osmoregulation in seawater.

Freshwater fish

Fish that live in fresh water; tend to take in salts from the environment and produce large volumes of dilute urine.

Sharks store lipids

Sharks store lipids and wastes in tissues to help maintain proper salt concentrations.