beetroot cell permeability

Question 1

aim

Answer 1

to investigate how temperature affects the permeability of cell membranes using beetroot

Question 2

what is the IV

Answer 2

temp/pH/solvent conc.

Question 3

what is the DV?

Answer 3

Absorbance of pigment/ permeability

Question 4

why should the size of the beetroot pieces be kept the same?

Answer 4

ensure surface area is consistent.

Question 5

control variables?

Answer 5

• same species of beetroot
• same sizes of beetroot
• volume of water/ethanol
• time beetroot is left in sol.
• same colour filter

Question 6

evaluation and improvements?

Answer 6

• Use a colorimeter instead of subjective color comparison.
• Repeat experiment and calculate mean absorbance for reliability.
• same species of beetroot
• use water bath

Question 7

outline a method a student could do to investigate the effect of temperature on beetroot cell membranes. (6 marks)

Answer 7

Prepare beetroot samples → Cut equal sizes, using cork borer + rinse to remove excess pigment.

Set up conditions → Different temperatures or ethanol concentrations.

Incubate → Leave for 20 minutes.

Measure permeability → Use a colorimeter to measure absorbance.

Interpret results → Higher absorbance = More pigment released = Higher permeability.

Question 8

results and interpretation?

Answer 8

• Increasing temperature → More kinetic energy → Phospholipids become more fluid → More pigment leaks.
• Very high temperatures (>60°C) → Proteins denature → Membrane structure breaks → Maximum permeability.
• Higher ethanol concentration → Dissolves phospholipids → Higher absorbance.

Question 9

using a colorimeter

Answer 9

• Set to a blue/green filter (as beetroot pigment is red).
• Calibrate with distilled water (absorbance = 0).
• Measure absorbance of each sample.