Name '~
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Date
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CHAPre
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Cell Energy: Phorosynthlssis and Res; »retion
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SKill
ACTIVITY-
Interpreting graphs
Section 6-1
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This Absor~)tion of Chlorophyll
A pigment is a substance that absorbs and reflects light of particular wavelengths. For example. the yellow-green color of a leal is due to a pigment in the leaf called cnloropnyll. When
white light (which contains alii at t~e colors d- the spectrum) shine.'; on chlorophyll. the
chlorophyll absorbs most of the red, orange, blue, and vh.1let and reflects most of the green and
yellow. That is why you see .!I yeilow..green ~:(.Ior.Think of a p.igment as a sponge that soaks up
all of the oilier colors of the spectrum except the one you see.
A spectrophotometer. is an instrument tha.t il used to meascre the amount of light absorbed
by a pigment. Below is a graph showing the lercentage of light energy reflected for the absorptlon spectrum for chlorophyll. The highest p~:Ws represent colors that chtorophyH ebsorbs
the most. Therefore. they are the least vislbl~,
AISOAP'ni.1N
Use the above' graph to
a.ns1~I<1N
1. Whichof the colors ~rbed
;-,
SPECTRUM FOA CHLOAoPtrl'''LL
the foUowin!i questions.
by
ehlG~~r'
2. What is its approximate wavelength?
is least visible?
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3. What percentag~ of light energy absorbfll1J does this peak represent?
4. How much of this color is being refiecu!(l?
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flfL
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Lli 7
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5. 'Nhat percentage of light energy ab.sorb<~dby chlorophyll does the orange spectrum ~
represent?
© Prentice-Hal!, Inc.
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6. Why would you say there are 110 peaks in l•.•t: l'anse between 5000 angstroms and 6100
angstroms?
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1. Are you able to see the light in the yellow-green part ot the spectrum? Explain why.
_
----'_._-------"----_._-----------------------8, Arrange the colors in the absorption spectrum -If chlomphyil in order of their visibility.
Place the most visible color first.
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PMOItl!T ~
100,
l.."GH'rViii KeY fl~CTiO
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60~
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50-1
40~'I
1
30
20j
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80~
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IV CHLOAOf'KYU.
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'~iL o I. --'--J-.-""""-I-.-.I.--A.o........bvi<;~
bit.""
QI'1 ~
yellow
Of'U.')9'i
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rid
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Use the bu graph. which shows t,he/pa.n:amag-. ot ii~~
'i energy refteemd by ch.loropbyU, to
answer the following questions. The graph wu c~
! from the chlorophyll~fPtion
spectrum.
9, \Vhich color in this spectrum is moot ••.
i.$lb~? _~
to.
\Vhat is the approximate pem!ntatrt o~light ~~
.
,
r refitl<:ted for this color?
_
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11. What percentage of llght mera.v ~
_
04 Ilight ~te'1Y refi,t'.:WQ is mibl4! to the hu.nlln eye. is red
12. If everytbing above 50 ~t
light part of the ~
dc.es ttli ~ ro!p~nt?
of
com ~Ieeil
in Ught ~l~!!ctedby c.l>t1oropb.yll? __ •. _~
__
~ Prentlce-Hall, lnc.
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