Diffusion & Osmosis


Diffusion & Osmosis


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.