CP5 Beetroot membrane

Question 1

What are 2 factors that affect membrane permeability?

Answer 1

• Temp.
• Conc. of solvents (ethanol + HCl).

Question 2

How is beetroot used to measure permeability of membranes?

Answer 2

• Higher permeability - more red pigment leaks out into solution in given time.
• Colorimeter can be used to measure absorbance ∴ conc. of pigment.

Question 3

Outline experiment to investigate affect of temp. on membrane permeability.

Answer 3

• Cut beetroot into 6 cylinders using a cork borer + scalpel.
• Weigh each cylinder.
• Heat 6 test tubes of water to different temps.
• Add a cylinder to each test tube.
• Leave each for 20 mins.
• Filter each solution into cuvette + measure absorbance.

Question 4

What are the safety hazards involved in using ethanol to measure membrane permeability?

Answer 4

• Irritant + flammable - keep away from naked flames + use eye protection.
• Keep scalpel away from fingers.
• Handle hot liquid w care.

Question 4

What is the effect of temp on membrane permeability?

Answer 4

• Increased temp results in increased permeability.
• Proteins in membrane denature + create gaps.

Question 5

What is the affect of ethanol on membrane permeability?

Answer 5

• Increased conc. leads to increased permeability.
• Ethanol emulsifies phospholipids in membrane causing gaps to form.