As temperatures decrease, membranes conform to a solid from a fluid state.

The plasma membrane exhibits selective permeability.

Phospholipids are amphipathic molecules, containing hydrophobic regions only.

Peripheral proteins are bound to the surface of the membrane

Integral proteins are bound to the surface of the membrane

Cells recognize each other by binding to surface molecules, often proteins, on the plasma membrane.

Hydrocarbons can dissolve in the lipid bilayer and pass through the membrane rapidly.

Sugars can dissolve in the lipid bilayer and pass through the membrane rapidly.

Carrier proteins bind to molecules and change shape to shuttle them across the membrane

Substances diffuse up their concentration gradient.

Osmosis: Water diffuses across a membrane from the region of higher solute concentration to the region of lower solute concentration

Isotonic solution is characterized by zero net water movement across the plasma membrane.

Hypertonic solution have solute concentrations that is greater than that inside the cell; therefore, the cell gains water.

Hypotonic solution have solute concentration that is less than that inside the cell, therefore, the cell gains water.

The sodium-potassium pump is one type of active transport system.

Pinocytosis is a form of exocytosis.

Polar molecules do not cross the membrane easily

Osmosis is the diffusion of water across a selectively permeable membrane.

Active transport allows cells to maintain concentration gradients that differ from their surroundings.