Effect of ethanol conc on membrane permeability

Question 1

What is the permeability of a membrane measured by?

Answer 1

Beetroot cells, which contain a purple pigment called betalain

Question 2

What are cell surface membranes made up of?

Answer 2

Phospholipid bilayer, which makes them partially permeable

Question 3

How can permeability be changed?

Answer 3

By solvents and temp

Question 4

What happens when the membrane has a higher permeability?

Answer 4

More pigment leaks out of cells

Question 5

What is the relationship between concentration and absorbance?

Answer 5

As the concentration increases, absorbance increases since cells gain a higher permeability

Question 6

Describe 1st part of method: Prep and leaving for 15 mins

Answer 6

1. Get 6 test tubes and put the different concs in them - 0%, 20%, 40%, 60%, 80%, 100%
2. Trim beetroot cylinders to 5mm + rinse with water then pat dry
3. Add 1 cyclinder to each tube + leave for 15 mins

Question 7

Describe 2nd part of method: Measuring absorbance

Answer 7

1. Swirl tubes + use forceps to remove cylinders
2. Pour remaining liquid into 6 cuvettes, fill another with distilled water
3. Distilled water will act as blank for colorimeter
4. Use colorimeter with green filter (520nm) to measure absorbance (AU) for each conc
5. Record results in table + plot graph