CP - CC3 - Investigation into the permeability of cell membranes using beetroot

How are cell membranes affected by an increase in temperature? (3)

heating the membrane can cause gaps to form between phospholipid molecules, the membrane becomes more permeable, protein in the membrane can be denatured by heat

Why are beetroot cells used in this experiment? (3)

beetroot cells contain beta lain, a bright red water soluble pigment in cell vacuoles, if the cell membranes are damaged pigment can escape from cells and be detected in aqueous medium around the tissue

What temperature does beetroot grow in soil?

10-15 degrees celsius

What apparatus is needed for this experiment? (10)

beetroot cylinders, white tile, 10 test tubes, scalpel, 250cm³ beaker, forceps, water baths, thermometer, stop clock, colorimeter with blue filter or colour chart

What temperature should water baths be set at? (5)

25, 35, 45, 55, 65 degrees celsius

Step 1

cut 5 pieces of beetroot into 1cm long cylinders

Step 2 (2)

Wash beetroot under running water, in order to remove pigment released from cells during cutting

Step 3

Place a test tube containing 5cm³ distilled water into each water bath to equilibrate for 5 minutes

Step 4

Place 1 piece of beetroot into each test tube for 30 minutes

Step 5 (2)

after 30 minutes shake the test tubes gently to make sure any pigment is well-mixed into the water, remove the beetroot cores from the test tubes

Step 6 (2)

Place a piece of white paper behind the test tubes to describe the depth of colours, arrange test tubes in order of temperature of the water bath

Step 7 (3)

set the colorimeter to respond to a blue/green filter, and to measure absorbance, check the colorimeter reading for distilled water

What wavelength is the blue/green filter of the colorimeter?

530 nm

Step 8 (2)

Measure the absorbance/percentage transmission of each tube, plot a graph of absorbance/percentage transmission against temperature

Outline the risk assessment for scalpels using ‘due to’ and ‘whilst’ (2)

Could cut skin due to using scalpel while cutting cylinders, cut away from body onto white tile

How should the beetroot cylinders be cut?

using a size 4 cork borer and cut with care using a cutting board