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Anthocyanins are coloured pigments found in the cell vacuole of some plant cells - AQA - A-Level Biology - Question 4 - 2020 - Paper 1
Question 4
Anthocyanins are coloured pigments found in the cell vacuole of some plant cells. Anthocyanins cannot move across undamaged cell membranes. A student investigated h... show full transcript
Worked Solution & Example Answer:Anthocyanins are coloured pigments found in the cell vacuole of some plant cells - AQA - A-Level Biology - Question 4 - 2020 - Paper 1
Step 1
Step 2
Step 3
Use your knowledge of membrane structure to explain the results in Figure 4.
Answer
The higher absorbance for extraction solvent E indicates that it extracted more anthocyanins. This may be due to ethanol's ability to disrupt the cell membranes, allowing more pigments to be released into the solution.
Solvent E, which contains acid, likely further enhances extraction by denaturing proteins that might otherwise impede the release of anthocyanins from the cellular structures. Conversely, the lowest absorbance recorded for solvent G (water) implies it is less effective in breaking down cellular barriers and extracting the pigments, as water alone cannot penetrate the membranes efficiently.
Step 4
Describe a method this student could use to prepare colour standards and use them to give data for the total anthocyanin extracted.
Answer
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Use known concentrations of blueberry juice or extract to create a series of standard solutions with varying anthocyanin concentrations.
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Measure the absorbance of these standard solutions using an alternative method, such as a colorimeter if available, or by visual comparison against known values.
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Compare the absorbance of the extracted solution to the standards to evaluate the total anthocyanin content extracted from the blueberries.