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After 1 hour, the student filtered the samples - AQA - A-Level Biology - Question 4 - 2020 - Paper 1
Question 4
After 1 hour, the student filtered the samples. She placed the filtrate in a colorimeter and measured the light absorbance. Her results are shown in Figure 4. Fig... show full transcript
Worked Solution & Example Answer:After 1 hour, the student filtered the samples - AQA - A-Level Biology - Question 4 - 2020 - Paper 1
Step 1
Higher absorbance indicates more anthocyanin
Answer
The results in Figure 4 show varying absorbance levels among the three extraction solvents E, F, and G. A higher absorbance reading generally indicates a higher concentration of anthocyanins released from the blueberries. Therefore, the order of absorbance suggests that extraction solvent E was most effective in releasing anthocyanins, followed by G, with F showing the least effectiveness.
Step 2
Higher absorbance indicates more membrane damage/permeability
Answer
In addition to the concentration of anthocyanins, higher absorbance could also result from increased membrane damage or permeability. The extraction process may have caused varying degrees of damage to the cell membranes of the blueberries, allowing more anthocyanins to be released into the solvent. This permeability effect could be significant for both E and G, indicating that these solvents may cause more membrane disruption compared to solvent F.
Step 3
Process of crushing blueberries
Answer
Crushing the blueberries releases some anthocyanins even before extraction. The potency of the extraction solvent in breaking down membranes can enhance this effect. Hence, the differences in absorbance could also stem from variations in cell structure integrity contributed by the crushing process.
Step 4
Impact of solvent composition
Answer
The differences in absorption levels among the solvents may also be attributed to their chemical composition. For instance, solvent E might consist of components that more effectively solubilize anthocyanins or alter membrane protein integrity, thereby increasing anthocyanin release when compared to solvents F and G.