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.

☐ 63.6 cm3 ethanol, 27.3 cm3 water, 9.1 cm3 acid

☐ 69.3 cm3 ethanol, 29.7 cm3 water, 1.0 cm3 acid

☐ 70.0 cm3 ethanol, 30.0 cm3 water, 1.0 cm3 acid

☐ 70.7 cm3 ethanol, 30.3 cm3 water, 1.0 cm3 acid

The student kept constant:

• the mass of fresh blueberries • the volume of extraction solvent • the time for 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.