4. photosynthesis experiments
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you can investigate the pigments in leaves using
chromatography
all plants contain
several different photosynthetic pigments in their leaves
each pigment absorbs a different
wavelength of light
having more than 1 type of pigment
increases the range of wavelenghts of light a plant can absorb
in addition to photosynthetic pigments some plants have other pigments in their leves which play other essential roles e.g.
protecting the leaves from excessive UV radiation
different species of plants contain
different proportions and micturres of pigments
what can you use to determine what pigments are present in the leaves of a plant
Thin Layer Chromatography (TLC)
like all chromatography TLC involves
a mobile phase (where molecules can move) liquid solvent a stationary phase (where molecules can’t move) solid plate with thin layer of gel on top
a sample of pigments can be extracted from the plants and put on the
TLC plate
when the TLC plate containg extract of pigments is placed in the solvent
solvent moves upwards through the gel carrying the dissolved pigments with it. some pigments travel faster or further than other pigments which seperates them out
its possible to identify a certain pigment by
calculting its Rf value and looking it ip in a database
what is the Rf value
the distance a substance has moved through the gel in relation to the solvent (each pigment has a specific Rf value) Rf value = disance travelled by spot / distance travelled by solvent qwqw