Diffusion Rates in Model Cells

Question 1

How can diffusion rates be investigated?

Answer 1

using model cells as they are easier to see and to work with

Question 2

What will the investigation involve?

Answer 2

a visible change e.g. colour change

it could be any of the following:

starch + potassium iodide

reducing sugar + benedicts reagent

pH indicator

Question 3

What will the investigation test?

Answer 3

factors that affect the rate of diffusion such as:

concentration gradient
diffusion distance
surface area
temperature

(THIS IS THE INDEPENDENT VARIABLE - CAUSE)

Question 4

What is the rate of diffusion?

Answer 4

dependent variable (EFFECT)

Question 5

What happens during the potassium iodide and starch investigation?

EXAMPLE

Answer 5

potassium iodide will diffuse into the model cell

time the colour change (clear to blue/black)

repeat at a range of either temps, or surface areas, or thickness of membrane, concentrations

minimumof 3 repeats

then calculate the mean