2. Exchange Across Cell Membranes: Diffusion

Question 1

define diffusion

Answer 1

the net movement of particles from an area of higher concentration to an area of low concentration , until molecules are evenly distributed

Question 2

is simple diffusion and faciliated diffusion an active or passive process?

Answer 2

passive

Question 3

when molecules diffuse directly through a membrane, it is called ——- diffusion

Answer 3

simple

Question 4

what proteins does facilitated diffusion use?

Answer 4

• channel
• carrier

Question 5

define polar molecules

Answer 5

they are charged, large particles, that would diffuse slowly directly through the membrane

Question 6

define non-polar molecules

Answer 6

, non charged particles,

Question 7

what are the function of carrier proteins

Answer 7

they move large molecules across the membranes, down their concentration gradient
1. a large molecule attaches to the carrier protein in the membrane
2. the protein changes shape
3. this releases the molecule on the opposite side of the membrane

Question 8

what is the function of channel proteins

Answer 8

they form pores in the membrane, for polar molecules to diffuse through (via their concentration gradient)

Question 9

list factors that can affect the rate of simple diffusion

Answer 9

• the concentration gradient: the higher the concentration gradient, the faster it is
• the thickness of the exchange surface: the thinner the exchange surface, the faster diffusion is
• the surface area: the larger the SA the faster the diffusion

Question 10

whats the difference between simple and facilitated diffusion?

Answer 10

simple diffusion means molecules can diffuse directly through the membrane at a fast speed, facilitated is where polar molecules diffuse via carrier or channel proteins

Question 11

what factors can affect facilitated diffusion

Answer 11

• the concentration gradient, the higher the concentration gradient, the faster the diffusion
• the number of carrier/channel proteins, the higher the number the faster facilitated diffusion can occur