BIOLOGY 5090 · STRUCTURED PRACTICE
1
A laboratory technician investigates the biochemical composition of an unknown fresh fruit juice extract.
(a)
[2]Describe the experimental procedure and positive result for testing the juice sample for the presence of reducing sugars.
(b)
[2]The technician uses DCPIP solution to measure the Vitamin C content of the fruit juice. State two variables that must be kept constant to ensure valid comparative results.
(c)
[2]Explain why boiled fruit juice requires a significantly larger volume of juice to decolourise 1.0 cm³ of DCPIP solution compared to fresh unheated fruit juice.
Total: 6 marks