Educational worksheet on cell transport mechanisms with labeled diagrams and questions.

- The cell membrane is selectively permeable, allowing some substances to pass while restricting others.
- Passive transport moves substances down their concentration gradient without energy input.
- Active transport moves substances against their concentration gradient and requires energy (ATP).
- Diffusion is the movement of molecules from high to low concentration until equilibrium is reached.
- Osmosis is the diffusion of water across a semipermeable membrane from low solute concentration to high solute concentration.
- Facilitated diffusion uses carrier proteins or channel proteins to move specific molecules down their concentration gradient.
- Endocytosis involves the cell membrane engulfing materials to bring them into the cell; exocytosis expels materials by fusing vesicles with the membrane.
- The sodium-potassium pump is an example of active transport that maintains electrochemical gradients in nerve and muscle cells.
- Vesicular transport includes phagocytosis (solids), pinocytosis (liquids), and receptor-mediated endocytosis (specific ligands).
- Hypertonic solutions cause cells to shrink (crenate) due to water loss; hypotonic solutions cause cells to swell (lyse); isotonic solutions maintain cell volume.