Cell Wall: The firm nonliving layer that encloses and supports the cells of

most plants, bacteria, fungi, and algae.

Plasma (cell) Membrane: The membrane found in cells that separates the

interior of the cell from the outside environment.

Fluid Mosaic Model: Describes the cell membrane as a combination of

several types of molecules that are constantly moving.

Osmosis: The net movement of water across a semipermeable membrane.

Passive Transport: Movement of substances across a cell membrane

without the expenditure of energy.

Active Transport: The use of energy by the cell to move substances across

the cell membrane.

Hypotonic Solution: Occurs when there is a lower amount of solute outside

the cell then there is inside the cell.

Hypertonic Solution: Occurs when there is a higher amount of solute

outside the cell than there is inside the cell.

Isotonic Solution: The amount of solute outside and inside the cell are

equal.

Phospholipid Bilayer: A two-layered arrangement of phosphate and lipid

molecules that form a cell membrane.

Selectively Permeable: Some molecules are allowed through while others

are not.