Biology Coursework

Hypothesis: To investigate the effect of different concentrations of ethanol on the permeability of beetroot cell membranes.

Prediction: By exposing a membrane to a solvent, ethanol, it will increase its permeability. So the higher the concentration of the solvent, the more permeable the membrane will be. But if the concentration of the ethanol is beyond a certain limit, it may break down the cell membrane to the point where there is in fact no overall effect as the ethanol would disturb the lipids in the membrane.

Therefore, more of the red pigment in the beetroot would leak as the lipids control the substances that enter and leave the cell membrane.

However the ethanol might also impair particular …show more content…
This is because of the change in pH to the cell membrane.

CONDUCTING THE EXPERIMENT

Apparatus: • Raw Beetroot • Scalpel • Ceramic tile • Tweezers • 10 Test tubes • Test tube racks • Measuring cylinder 25cm3 • Colourimeter • Cuvettes • Pipette • Stopclock • Ruler

Control Variables: 1. Volume of the solution 2. Length of time beetrootss left in solution 3. Diameter of beetroot 4. Size of the beetroot

Safe working environment: 1. Ethanol:
Corrosive and highly flammable. Irritating to skin and eyes. Can be damaging if large amount is splashed into eyes. Intoxicating if ingested. If ingested in undiluted form, it has a severe drying effect on mucous membranes of mouth and throat. Intoxicating if continuously inhaled for a long period of time. 2. Spillages:
Safety hazard, inhalation if not cleared, corrosive and room needs to be well ventilated even without spillages. 3. Scalpels:
Cutting the beetroot – white tile needed and cautious of a sharp implement 4. Gloves:
Beetroot pigment stains clothes, therefore gloves are useful with the use of beetroot as well the usage of ethanol, as it is skin irritant.

Method: • Using the scalpel and ruler, cut strips of beetroot with an area of 1cm2 • Thoroughly rinse cut beetroot with distilled water to ensure excess pigment will not affect the overall results • Prepare test tubes for the