guys today I'm gonna talk about trapping
light energy okay so let's get started
chloroplast contains several different
pigments and these different pigments
absorb different wavelengths of light
the photosynthetic pigments of higher
plants form two groups the chlorophyll
and the carotenoids and chlorophyll is
observed mainly in red and blue violet
regions of the light spectrum they
reflect green light which is why plants
look green chlorophyll is observed
mainly in red and blue violet regions of
the light spectrum they reflect green
light which is why plants look green the
structure of chlorophyll a is shown in
here and carotenoids absorb mainly in
fluvial region of the spectrum an
absorption spectrum is a graph of the
absence absorbance of different
wavelengths of light by a pigment an
action spectrum is a graph of rate of
photosynthesis at different wavelengths
of light and this shows the
effectiveness of the different
wavelengths which is of course related
to their absorption and to their energy
content the shorter the wavelength the
greater the energy is it contains if you
illuminate a solution of chlorophyll a
or B with ultraviolet light you will see
a red fluorescence and in the absence of
safe ultraviolet light you can
illuminate the pigment with with a
standard fluorescence tube so the
ultraviolet light is absorbed and
electrons are excited but in a solution
that will contain extracted pigment the
absorbed energy can not usefully be
passed on to do work and the electrons
returned to their an excited state and
the observed energy
is transferred to the soundings as
thermal energy and as light at a longer
less energetic and wavelength than that
which was absorbed and is seen as the
red fluorescence in in the functioning
photosynthetic system it's these energy
that drives the process of
photosynthesis so you can easily extract
chloroplast pigment from and live to see
how many pigments are present by using
paper chromatography is shown in here
and you can calculate the RF value for
which for each pigment using this
equation so equation is RF equal to
distance traveled by pigment poor spot
divided by distance traveled by solvent
so these will vary depending on the
solvent used but in general caroteniods
have Rf values close to one and
chlorophyll b has a much lower Rf
value and chlorophyll a has an RF value
between those of carotenoids and
chlorophyll b so guys that's all thank
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