An Investigation to Show How Water Temperature and Alcohol Concentratio

An Investigation to Show How Water Temperature and Alcohol Concentration Affect Membrane Permeability Aim The aim of the experiment is to show the cell’s membrane permeability is affected by being placed into different temperatures of water. Also the effect of placing beetroot in to different concentrations of alcohol. Beetroot cells contain a red sap, which leaks out of the cells if their membranes are damaged or altered. Cell membranes are made up of a bilayer of phospholipids, which also contains proteins. Which either float around or are fixed. Some are found in the inner or outer layer and some span the whole membrane Carbohydrate chains attach themselves to the external membrane forming glycoproteins and glycolipids. It also contains cholesterol. We will be able to tell how damaged they are because we will see a deeper coloured red in the water from where more of the red sap has leaked out of the cells. Method A fresh cylinder of beetroot was taken and using a scalpel any skin was removed. Care should be taken when a scalpel is used to cut objects into small pieces. It was then cut into 40 discs using the scalpel. Next the discs were placed in a boiling tube and rinsed repeatedly in till the water ran clear. Then two sets of five boiling tubes were set up into racks. Then using a measuring cylinder measured 10cm ³ of tap water was placed in five of the boiling tubes of the set that would be testing the effect of different temperatures. These were then left in the different water baths to adjust to the temperature. The other five had 10cm ³ different concentrations of alcohol ranging from 25%-100%. There was also one with 10cm ³ of water. Next four discs of the beetroot were placed into each boil... ...es down to 24%. I think this an anomalous result as after researching this 100% alcohol is used to preserve food so the light transmission percentage should of gone up but this needed to be repeated. I think the main source of error in these two experiments that could have lessened the accuracy was that there was some variation in the thickness of some of the beetroot discs. I think this is hard to improve as this is generally down to human error of not being able to cut beetroot exactly into 1-2mm discs. The experiment needed to be repeated to see more clearly if there were any anomalous results. Works Cited: Advanced Sciences Biology 1, Mary Jones, Richard Fosbery and Dennis Taylor AS guru Biology, John Graham and Anthony Lewis Biology Principles and Processes, Michael Roberts, Michael Reiss and Grace Monger Www.bbc.co.uk/asguru/biology