A-Level AQA Biology DNA, Genes & Chromosomes: A student investigated how to ex

Question

A student investigated how to extract anthocyanins from blueberries.

She mixed 10 g of crushed, fresh blueberries with 100 cm³ of extraction solvent for 1 hour.

She investigated three different extraction solvents:

E – Ethanol, water and acid
F – Ethanol and water
G – Water

When making up extraction solvent E, the student used a volume ratio of 70:30:1 ethanol:water:acid.

Tick (✓) one box that shows the most appropriate volumes she would use to make up 100 cm³ of extraction solvent E.

69.3 cm³ ethanol, 29.7 cm³ water, 1.0 cm³ acid

The student kept constant:
1. The mass of fresh blueberries
2. The time of the mixture to stand.

Name two other variables the student should have kept constant during this investigation.

1
2

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.

Use your knowledge of membrane structure to explain the results in Figure 4.

A different student did this investigation. He did not have a colorimeter.

Describe a method this student could use to prepare colour standards and use them to give data for the total anthocyanin extracted.

A student investigated how to extract anthocyanins from blueberries - AQA - A-Level Biology - Question 4 - 2020 - Paper 1