Diffusion

Question 1

What is diffusion?

Answer 1

net movement of particles from a region of higher concentration to a region of lower concentration

it is passive and will continue until there is a concentration equilibrium between the 2 areas

Question 2

What factors affect the rate of simple diffusion?

Answer 2

temperature - the higher the temperature the higher the rate of diffusion because the particles have more KE

concentration difference - greater the difference the faster the diffsuion

Question 3

What substances can diffuse across the phospholipid bilayer?

Answer 3

non polar molecules such as O2 can diffuse freely down a concentration gradient

the hydrophobic interior of the membrane repels substances with charges

polar molecules can diffuse through membranes but at a slow rate

Question 4

What is meant by the term partially permeable?

Answer 4

only permeable to some molecules

small polar molecules pass through the membrane more easily than large ones

Question 5

What is the rate at which molecules diffuse across membranes affected by?

Answer 5

surface area - the larger the surface area the higher the rate of diffusion

thickness of the membrane - the thinner the exchange surface, the higher the rate of diffusion

Question 6

What is facilitated diffusion?

Answer 6

using channel proteins through which polar molecules and ions can pass

protein channels are selectively permeable to one specific molecule or ion