Diffusion- is the process by which molecules move across the cell membrane from an area of higher concentration to an area of lower concentration. For a picture of diffusion you can look in the text book on page 187.

Osmosis- is the diffusion of water molecules through a seletively permeable membrane.
The red dots are the water molecules.

Active Transport- is an energy-requiring process that lets materials move across a cell membrane from lower concentration to higher concentration. In the text book on page 189 there is a picture of active transport.

Passive Transport-is a process that DOES NOT require energy. A molecule moving from a higher concentration to a lower concentration. Diffusion and osmosis are both types of passive transport.

Endocytosis- is a process of taking in material into the cell by pockets in the cell membrane.
Exocytosis- when larger molecules are removed from the cell.