B2 - Simple Transport

Question 1

What is diffusion?

Answer 1

Diffusion is the net movement of particles from an area of high concentration to an area of low concentration which happens along a concentration gradient.

Question 2

What happens eventually with diffusion?

Answer 2

Eventually an equilibrium is reached where there is an equal amount of particles on each side.

Question 3

What factors affect the rate of diffusion? (5)

Answer 3

Temperature
Distance particles need to travel over
Size of concentration gradient
Size of particles
Surface area of diffusion

Question 4

How is diffusion maximised?

Answer 4

EXCHANGE SURFACES try and maximise diffusion by trying to maximise their surface area by having ridges or folds.
They often have thin walls or membranes to give a short distance for particles to travel.
They have a good blood supply.
They try and maintain a constant, high concentration gradient.

Question 5

Why is diffusion important for respiration?

Answer 5

Diffusion is important for respiration because oxygen in the red blood cells needs to diffuse to other cells. Particles move down the concentration gradient. Cells need oxygen so diffusion gives it to them by allowing oxygen to move into the cells.