Unit 3 Part B: Rate of Diffusion

Question 1

What factors influence rate of diffusion?

Answer 1

1)Steepness of gradient
2) Temperature
3)Solute size (molecular weight)
4) Membrane permeability
5) Amount of membrane surface area available for transport

Question 2

How does temperature affect the rate of diffusion?

Answer 2

The warmer a substance, the more rapidly its particles diffuse. (sugar diffuses more quickly through hot tea than iced)

Question 3

How does molecular weight affect the rate of diffusion?

Answer 3

Heavy molecules (proteins) move sluggishly and diffuse slower than light particles (electrolytes/ gases). Small molecules pass through membrane pores easier than large ones

Question 4

How does steepness of the concentration gradient affect diffusion?

Answer 4

Steepness of a gradient refers to the concentration difference between two points. Particles diffuse more rapidly if there is a grater concentration difference (ball rolling faster down a steeper slope)

Question 5

How does membrane surface area affect rate of diffusion?

Answer 5

The atypical surface of cells specialized for absorption (small intestine) is often folded into microvilli. That makes more membrane available for particles to diffuse through

Question 6

How does membrane permeability affect rate of diffusion?

Answer 6

A membrane with smaller surface area or lower permeability will impede molecular movement and thus lead to slower diffusion.