Passive Transport

Two main points:

• 1) Needs no energy (ATP)

• 2) Substances move from greater to lesser concentration.

Types of Passive Transport

• 1) Diffusion

• 2) Osmosis

• 3) Facilitated Diffusion

Diffusion animation

• Diffusion is:

The movement of molecules from an area of high concentration to an area of lowconcentration.

Diffusion Video

• 1. Simple diffusion is defined as the movement of:

• A) molecules from areas of higher concentration to areas of lower concentration.

• B) molecules from areas of lower concentration to areas of higher concentration.

• C) water molecules across a membrane.

• 2. When sugar is mixed with water, equilibrium is reached when

• A) molecules of sugar stop moving.

• B) water and sugar molecules are moving at the same speed.

• C) the dissolved sugar molecules are evenly distributed throughout the solution.

• 3. The molecules in a solid lump of sugar do not move.

• A) True

• B) False

• 4. Diffusion is one of the processes whereby materials are exchanged between a cell and its environment.

• A) True

• B) False

Osmosis animation

• Osmosis is:

The movement of water molecules from an area of high concentration to an area of low concentration.

Osmosis Video

1) Osmosis is best defined as the movement of

• A) molecules from an area of high concentration to an area of lower concentration.

• B) molecules from an area of low concentration to an area of higher concentration.

• C) water molecules across a membrane from an area of low water to an area of higher concentration.

• D) water molecules across a membrane from an area of high water concentration to an area of lower concentration.

2 Which of the following will pass through a cell

membrane most easily?

• A) small polar molecules

• B) small nonpolar molecules

• C) large polar molecules

• D) large nonpolar molecules

• E) large neutral molecules

3. A red blood cell placed in a hypertonic medium will:

• A) expand.

• B) burst.

• C) shrink.

• D) have no change in shape.

4 A 5% urea solution is hypotonic to a 10% urea solution.

• A) True

• B) False

5. If a cell is placed in an isotonic medium, there will be no net movement of water.

• A) True

• B) False

Facilitated Diffusion

• Facilitated diffusion is:

The movement of molecules from an area of high concentration to an area of low concentration through a channel protein.