Required Practical 3 - producing a dilution series and calibration curve

calculating dilutions

C₁ x V₁ = C₂ x V₂

collecting data

dilution series

use scalpel to cut identical cylinders

blot dry to remove excess water and record initial mass

immerse one piece of plant tissue in each solution for a set time

blot dry to remove excess liquid and record final mass

repeat 3 times

processing data

calculate % change in mass = (final - initial mass)/ initial mass

plot graph with concentration on x axis and percentage change on y axis

identify where line of best fit sits at 0% change in mass (finding the water potential equal to the plant tissues water potato)

use table to find exact water potential

control variable when making dilution series

volume of solution

control variable when cutting cylinders of plant tissue

-size, shape and surface area

-source of plant tissue

control variable when immersing plant tissue

length of time in solution

Temperature

shake to ensure all surfaces exposed

reason for using percentage change in mass

allows comparison as initial masses of plant tissue were different