required practical 4

Question 1

two factors which affect the permeability of the cell membrane

Answer 1

temperature
concentration of solvents (ethanol)

Question 2

how is beetroot used to measure permeability of the cell membrane?

Answer 2

the higher the permeability, the more red pigment that leaks out

Question 3

method

Answer 3

1. cut beetroot into 6-10 identical cubes with a scalpel
2. clean any excess pigment
3. if investigating temp: place each cube in an equal volume of distilled water and place in a water bath at different temps (30-80)
4. if investingating conc.: create a dilution series of ethanol and distilled water from 0 to 100% ethanol
5. leave samples for 20 minutes
6. set colorimeter to blue and zero
7. filter each sample into cuvette
8. measure absorbance

Question 4

what does a higher absorbance indicate?

Answer 4

a more permeable membrane

Question 5

what is the effect of temperature on permeability?

Answer 5

increased temperature increases permeability

Question 6

what is the effect of ethanol on permeability?

Answer 6

increased ethanol increases permeability

Question 7

dilution series calculation

Answer 7

C1 x V1 = C2 x V2
V2 = V1 + volume of distilled water to dilute with
c1- concentration of stock solution
v1 - volume of stock solution used to make new concentration
c2 - concentration of the solution you are making
v2- volume of new solution you are making