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Date November 2017 Marks available 3 Reference code 17N.3.HL.TZ0.01
Level Higher level Paper Paper 3 Time zone TZ0 / no time zone
Command term Explain Question number 01 Adapted from N/A

Question

 

Outline what happens when spinach extract is spotted on a TLC plate and placed into a container of solvent.

[2]
a.

Explain what the Rf values represent in chromatography.

[3]
b.

State two photosynthetic pigments that could be identified using chromatography.

 

[1]
c.

Markscheme

a. solvent will move up «the TLC plate/stationary phase»

b. pigments will move up «the TLC plate/stationary phase carried by solvent»

c. pigments will move at different rates/separate

[Max 2 Marks]

a.

a.

     OR

    distance moved by pigment relative to distance moved by solvent

b. each pigment has/is represented by a specific Rf «value»

c. used to identify different pigments

d. Rf «value» depends on density/solubility/polarity of the pigment in solvent

Allow “compound” or “molecule” instead of pigment

[Max 3 Marks]

b.

chlorophyll
carotene
xanthophyll

Accept other valid pigments

Do not accept pigments named by colour

Award [1] for any two correct

Award [1] for chlorophyll a AND (chlorophyll) b

[Max 1 Mark]

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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