Core Practical 3 / Biology / By Fawaza Faleel Investigate membrane properties including the effect of alcohol andtemperature on membrane permeability. MARKING SCHEME More RECOMMENDED ADDITIONAL PRACTICAL 1 Investigate tissue water potentials using plant tissue and graded concentrations of a solute. RECOMMENDED ADDITIONAL PRACTICAL 2 Use a semi-quantitative method to estimate protein concentration using biuret reagent and colour standards.