Diffusion & Osmosis
Notes
What is Diffusion?
 The movement of particles from regions or areas of _________ concentration
(crowded) to areas of ________ concentration (less crowded) is called
____________.
 Look at Figure 1 on pg. 78!
 The dye moved from an area of high concentration and spread to the area of low concentration.
 Ex. when oxygen diffuses into the cell and carbon dioxide diffuses out.
Diffusion of Water
 Diffusion also happens with and between living cells.
 The cells of organisms are surrounded by and filled with fluids that are made mostly of ________.
 The diffusion of water through a ____________________ (partially allows things through) membrane is so important that it has been given a special name- __________.
 Look at Figure 2 on pg. 79!
Moving Small Particles
 In a cell, the movement of particles across a cell membrane _________ the use of energy by the cell is called __________ ___________.
 During passive transport, particles move from an area of _______ concentration to an area of _______ concentration.
 Examples:__________ & __________
 A process of transporting particles that requires the cell to use energy is called ________ ____________.
 Active transport usually involves the movement of particles from an area of
_______ concentration to an area of _______ concentration.
 Ex. when iron diffuses into the cell using active transport because the iron molecules are too large.
Moving Large Particles
 The active transport by which a cell surrounds a large particle, such as a large
_________, and encloses the particle in a vesicle to bring the particle into the cell is called _______________.
 Vesicles are _____ formed from pieces of cell membrane.
 When large particles, such as ________, leave the cell, the cell uses an active transport called ______________.
 During exocytosis, a vesicle forms around the large particle, carries the particle to the cell membrane, fuses with the cell membrane, and releases the particle outside of the cell.