Diffusion

Question 1

What is diffusion?

Answer 1

The net movement of particles from an area of higher concentration to an area of lower concentration.

Question 2

Do particles diffuse up or down the conc grad?

Answer 2

Down

Question 3

Is diffusion passive or active?

Answer 3

Passive - does not require energy.

Question 4

What factors affect the rate of diffusion?

Answer 4

1. Conc grad - higher = faster rate
2. Thickness of exchange surface - thinner = faster rate
3. Surface area - larger = faster rate

Question 5

What is facilitated diffusion?

Answer 5

The diffusion of particles through carrier proteins or channel proteins in the plasma membrane

Question 6

How do carrier proteins work?

Answer 6

1. Large molecule attached to carrier protein
2. Protein changes shape
3. Releases the molecule on opposite side of membrane

Question 7

How do channel proteins work?

Answer 7

Form pores in the membrane for charged particles to diffuse through

Question 8

What factors affect the rate of facilitated diffusion?

Answer 8

1. Conc grad - higher = faster (until a point)
2. Number of channel/carrier proteins (once all in use facilitated diffusion can’t happen any faster unless conc grad is increased)