Practise IB Biology SL 1.3.4 by using thin-layer chromatography, pigment distances and Rf values to identify photosynthetic pigments.
Pigments were extracted from spinach (Spinacia oleracea) leaves and separated on a thin layer chromatogram.
Removed for copyright reasons
Describe how the spinach leaf pigment extract should be applied to a chromatogram so that the pigment bands separate clearly.
a
small drops applied
OR
use fine needle/pipette
Need idea of 'small'
2 max
b
several drops applied «to get strongly coloured spot»
c
each drop must be dry before the next is applied
d
drops applied to the origin/baseline/bottom line/just above the level of the solvent
End is too vague
State one advantage of using thin layer chromatograms over paper chromatograms.
TLC develops faster
OR
clearer separation/colours/bands/spots «on a TLC»
OR
easier to calculate the Rf values
OR
shorter chromatograms can be used
OR
TLC uses less solvent
Clearer alone is not enough for the mark, candidates must state what is clearer
1 max