| Date | November 2017 | Marks available | 3 | Reference code | 17N.3.SL.TZ0.02 |
| Level | Standard level | Paper | Paper 3 | Time zone | TZ0 |
| Command term | Explain | Question number | 02 | Adapted from | N/A |
Question
Thin-layer chromatography was carried out on red and brown algae to discover what photosynthetic pigments they contained. The results were compared with the known pigments found in spinach leaves.
Identify pigment labelled P.
State a suitable solvent for extracting photosynthetic pigments from plant tissue.
Explain how the pigments in the chromatogram of spinach are identified.
Markscheme
xanthophyll
acetone
OR
alcohol
OR
ether
Accept other named organic solvent
If there is more than one answer accept only the first one. (Note: “Water mixed with alcohol” would be correct as would “alcohol, water” but “water, alcohol” would be incorrect)
a. they can be identified by their colour/analysis with spectrometer
b. measure the distance travelled by the solvent front
c. measure the distance travelled by the pigment
d. calculate the Rf value
e. they can be identified by comparing Rf values to known values
[Max 3 Marks]
