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Date November 2017 Marks available 3 Reference code 17N.3.SL.TZ0.02
Level Standard level Paper Paper 3 Time zone TZ0 / no time zone
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.

[1]
a.

State a suitable solvent for extracting photosynthetic pigments from plant tissue.

[1]
b.

Explain how the pigments in the chromatogram of spinach are identified.

[3]
c.

Markscheme

xanthophyll

a.

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)

b.

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]

c.

Examiners report

[N/A]
a.
[N/A]
b.
[N/A]
c.

Syllabus sections

Core » Topic 2: Molecular biology » 2.9 Photosynthesis
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