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Question 17N.3.SL.TZ0.02

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Date November 2017 Marks available [Maximum mark: 5] Reference code 17N.3.SL.TZ0.02
Level SL Paper 3 Time zone TZ0
Command term Explain, Identify, State Question number 02 Adapted from N/A
02.
[Maximum mark: 5]
17N.3.SL.TZ0.02

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.

(a)

Identify pigment labelled P.

[1]

Markscheme

xanthophyll

(b)

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

[1]

Markscheme

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)

(c)

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

[3]

Markscheme

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]

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