Diffusion

Question 1

What is the definition of diffusion?

Answer 1

The passive movement of a molecule or ion down a concentration gradient, from a region of higher concentration to a region of lower concentration

Question 2

What are the six factors that can affect the rate of diffusion?

Answer 2

Concentration gradient
Thickness of the surface
Surface area of the membrane
Size of the diffusing molecule
Nature of the diffusing molecule
Temperature

Question 3

How does the concentration gradient affect the rate of diffusion?

Answer 3

Greater the difference in conc. of molecules in two areas, the more molecules will diffuse in a given time

Question 4

How does the thickness of the surface affect the rate of diffusion?

Answer 4

The shorter the distance over which diffusion takes place, the more molecules will diffuse in a given time

Question 5

How does the surface area of the membrane affect the rate of diffusion?

Answer 5

The larger the area the higher the number of molecules that will diffuse in a given time

Question 6

How does the size of the diffusing molecule affect the rate of diffusion?

Answer 6

Smaller molecules diffuse faster than larger molecules (more kinetic energy)

Question 7

How does the nature of the diffusing molecules affect the rate of diffusion?

Answer 7

Molecules that are soluble in phospholipid (non-polar) diffuse faster than water soluble molecules (polar) because they can diffuse anywhere through the membrane

Question 8

How does the temperature affect the rate of diffusion?

Answer 8

Increased temperature increases the rate of diffusion as the molecules or ions have more kinetic energy

Question 9

How do you calculate the rate of diffusion?

Answer 9

Rate of diffusion = surface area x difference in concentration / length of the diffusion path