Practical 2: Estimation of osmolarity in tissues by bathing samples in hypotonic and hypertonic solutions. (Topic 1: Cells - 1.4 Membrane Transport)
The emphasis on this practical is the need for accurate measurements in scientific experiments. In this case the measurements for length and mass can be compared. Do they both suggest the same concentration, if not why? Which measurement is likely to be the most accurate and why?
This experiment also allows you to develop skills in the following mathematical skills:
perform the basic arithmetic functions: addition, subtraction, multiplication and division
carry out calculations involving means, decimals, fractions, percentages and ratios
plot graphs (with suitable scales and axes) involving two variables that show linear or non-linear relationships
calculate and analyse standard deviation
First: work out the difference between the two numbers you are comparing.
Change = New Number - Original Number
Then: divide the increase by the original number and multiply the answer by 100.
% change = change ÷ Original Number × 100.
If your answer is a positive number then it is percentage increase, if it is a negative number then this is a percentage decrease.