| A | B |
|---|
| cell membrane | part of the cell's outer boundary; contains a lipid bilayer. |
| lipid bilayer | principle component of a cell membrane |
| cell wall | Structure produced by some cells outside their cell membrane; variously composed of chitin, peptidoglycan, or cellulose. |
| passive transport | Movement of substances across the cell membrane from regions of high concentration to regions of low concentration; occurs without the cell expending energy.. |
| diffusion | process by which substances spread through a liquid or gas from regions of high concentrations to regions of low concentration. |
| osmosis | diffusion of water through a selectively permeable membrane. |
| facilitated diffusion | the diffusion of particles across a selectively permeable membrane with the assistance of transport proteins that are specific in what they will carry and have a binding site designed for certain molecules of interest. This process requires no energy. |
| active transport | movement of a substance against a concentration difference; a process that requires energy. |
| hypertonic | characterizes a solution that has a higher solute concentration than does a neighboring solution. |
| hypotonic | characterizes a solution that has a lower solute concentration than a neighboring solution. |
| isotonic | solution that has the same solute concentration as surrounding solutions. |
