Objective:
To investigate the effect of different organic solvents, such as alcohol and paraffin oil, on the cell membrane of the beetroot by using the red pigments in the beetroot as indicator.
Hypothesis:
Organic solvents dissolve the organic matter in the cell membrane (such as phospholipids). This destroys the cell membrane, and the permeability of the cell membrane is disrupted casing red pigments to leak out by diffusion.
Biological principle:
The cell membrane is mainly made up of phospholipids and proteins. The phospholipid molecules are arranged in a bilayer. And there are some proteins molecules are interspersed among the phospholipid bilayer. This structure makes the cell membrane differentially permeable. Thus, some large molecules can’t pass through the cell membrane. The cell membrane can be destroyed by physical damage and chemical. When the cells are cut, the cell membranes are mechanically ruptured. Some chemicals such as organic solvents can dissolve the organic matter in cell membrane, causing damage of the membrane and therefore increased permeability. This leads to an easier leakage of contents of the cell.
Type of variables
Representing variables in this experiment
Dependent variable
Color of the organic solvents change
Independent variable
Concentration of organic solvents and kinds of organic solvents
Control variable
Temperature of organic solvents used and the surrounding
Volume of organic solvent used
Time for the reaction
Control set-up: 3 ml of water with beetroot for 5minutes reaction
This set-up are used to show if there are the same effect as in organic solvents
Assumptions:
The volume of the red pigments in each of the beetroot cell is equal.
Materials:
Water, 10% alcohol, 20% alcohol, 30% alcohol, paraffin oil
Apparatus:
Beaker X1, cloth X1, test tube X6, test tube rack X1, forceps X1, measuring cylinder