3.4 Bio

​IV. Diffusion and Osmosis (3.4)

​A. Passive transport- allows cell to move materials across cell membrane without using energy

1. Diffusion- Movement of materials (fluid or gas) from region of high concentration to region of low concentration

​a. Concentration gradient- used to describe areas of high and low concentration.

b. When movement makes concentration equal- reaches dynamic equilibrium (Molecules still continue to move- dynamic)

c. Diffusion plays important role in movement of carbon dioxide and oxygen molecules

Multiple Choice

What plays an important role in movement?

• Diffusion

• Oxygen

• Concentration Gradient

• Osmosis

Multiple Choice

What allows materials to cross the cell membrane without using energy?

• Passive transport

• Photosynthesis

• Enzymes

​2. Osmosis- Diffusion of water molecules

​

a. Three terms used to describe the amount of dissolved particles in cell compared to   amount of water (terms are comparisons)

1). Isotonic- same concentration of dissolved materials (water moves in and out at equal rate)

​ 2). Hypertonic- solution has higher concentration of dissolved materials (Water concentration higher in cell than outside- water moves out of cell

​3). Hypotonic- Solution has lower   concentration of dissolved materials (water moves into the cell) 

Multiple Choice

Which of these have a higher solution of dissolved materials?

• Isotonic

• Hypertonic

• Hypotonic

Multiple Choice

Which of these have the same solution of dissolved materials?

• Isotonic

• Hypertonic

• Hypotonic

Multiple Choice

Which of these have the lower solution of dissolved materials?

• Isotonic

• Hypertonic

• Hypotonic

​B. Facilitated diffusion- larger molecules can still diffuse through openings formed by transport proteins

​ 1. Still form of passive transport

  2. Many types of transport proteins- most allow only certain molecules to travel into cell

Multiple Choice

Larger molecules can still diffuse through openings formed by ___ ?

• Active Transport

• Passive Transport