Here's a breakdown:

* Permeable: Allows all substances to pass through freely.

* Impermeable: Prevents all substances from passing through.

* Semipermeable: Selectively allows some substances to pass through while blocking others.

Examples of semipermeable membranes:

* Cell membranes: The outer layer of cells that controls what enters and exits the cell.

* Dialysis tubing: Used in medical treatments to filter blood.

* Some types of plastic wrap: Allows moisture to escape while keeping food fresh.

Factors that determine permeability:

* Size of molecules: Smaller molecules can pass through more easily.

* Charge of molecules: Charged molecules may be repelled by the membrane.

* Solubility in lipids: Molecules that are soluble in lipids (fats) can pass through more easily.

Key processes that involve semipermeable membranes:

* Diffusion: Movement of molecules from an area of high concentration to low concentration.

* Osmosis: Movement of water across a semipermeable membrane from an area of high water concentration to low water concentration.

* Active transport: Movement of molecules against their concentration gradient, requiring energy.

Let me know if you'd like more information on any of these concepts!