Describe5 marksChallenge
A student carried out biochemical tests on four colourless solutions, P, Q, R and S. The results are shown in the table.
| Test | P | Q | R | S |
|---|---|---|---|---|
| Benedict's test | Blue → brick-red precipitate after 1 min | Blue → brick-red precipitate after 5 min | Blue → no change | Blue → no change |
| Benedict's test after acid hydrolysis | Not tested | Not tested | Blue → brick-red precipitate | Not tested |
| Iodine test | Yellow-brown → no change | Yellow-brown → no change | Yellow-brown → no change | Yellow-brown → blue-black |
| Emulsion test | No white cloud | No white cloud | No white cloud | No white cloud |
| Biuret test | No purple colour | No purple colour | No purple colour | No purple colour |
Describe how the student would use these results to identify which type of biological molecule is present in each solution.