Identify the implementation weakness, explain its effect on variability or inference and propose additional readings, equipment or controls that address it directly.
Beetroot cells contain a red pigment called betalain. This pigment does not leak out of the cells, unless their membranes are damaged.
A student investigated the effect of detergent on beetroot cell membranes.
Discs of tissue were cut from a beetroot. Any betalain on the outside of the discs was removed.
One disc was placed into each of five test tubes, containing 0.2% detergent solution.
The five tubes were left for 30 minutes at 20∘C.
The discs were then removed carefully.
Betalain had leaked from the discs and formed a red solution in each test tube.
Light was shone through this solution. The percentage of the light transmitted through the solution was recorded.
The same procedure was repeated using detergent concentrations of 0.0%,0.5%, 1.0% and 2.0%.
Explain why five discs were used for each concentration of detergent.
An explanation that includes the following points:
- to calculate standard deviation / measure reliability / variability (1)
- to identify anomalies (1)