Solved by a verified expert:Photosynthesis
and Respiration
Margaret E. Vorndam,
M.S.
Version42-0103-00-01
Lab Report Assistant
Thisdocumentisnotmeanttobeasubstitute foraformallaboratoryreport.TheLabReport Assistantissimplyasummaryoftheexperiment’squestions,diagramsifneeded,anddatatables
that
shouldbeaddressedinaformallabreport.
Theintentistofacilitatestudents’writing
oflab reports by providing
this informationin an editable
filewhich can be sent to an instructor.
Observations
Data
Table 1: Rf Value Comparison for Chlorophyll Pigments
Chlorophyll
Pigment
Observed
Color
Distance to top
ofpigment,mm
Rf
Other
Students’ Rf
Average
# of Rf Results Averaged
from other Students (N)
Top of Solvent
Front
NA
Carotenoids
Xanthophylls
Chlorophyll
a
Chlorophyll
b
Distancetotopofpigment,mm:Measurefromwherethetopofthesolventextractlevel
intersectedthepaperchromatographtothetopmostlevelofthecolor.Thenmeasurethis
distance
to the top of the solvent front and record.
Data
Table 3: Gross Photosynthesis
in Elodea
Rates
Distance
of travel, mm
Net Photosynthesis
Rate
over
10 minutes
= mm of movement from
marked beginning point on bent
tube to end point after10
minutes
RespirationRate over 10 minutes
= mm of movement from
marked end point on bent
tube
toward beginning point after10 minutes
Gross Photosynthesis
over
10 minutes
(= mm Net Photosynthesis
+ mm Respiration)*
Rate
of Photosynthesis over
one hour
(= Gross Photosynthesis
÷ 10 minutes x 60 minutes)
*Was respirationoccurring
during photosynthesis? Add back the
O2that was
consumed by plant respirationto obtain the total photosyntheticrate.
Data
Table 4: Comparison of PhotosyntheticRate
My PhotosyntheticRate Result
Average
of Other Students’ PhotosyntheticRate
Results
N = (number of data averaged)
Data
Table 4: Observationof pH Change in the Oxygen
Cycle
Contents of
Respirometer
Initial
Color
T0, minutes
Final
Color
T1,minutes
Total
timefor color change,
T1– T0,minutes
Elodea,
Bromothymol
blue
solution
Elodea, Bromothymol blue solutionin foil
Data
Table 5: Comparison of PhotosyntheticRate
My Result:
Total timefor color
change,
T1– T0,minutes
Average
of Other Students’ Results: Total timefor
color change,
T1– T0,minutes
N = (number of data averaged)
Elodea, Bromothymol
blue solution
Elodea, Bromothymol
blue solutionin Foil
Exercise
1: Chlorophyll Pigments
Results
Rf = distance
to top
of pigment in mm ÷ distance
to top
of solvent front.
Rf Average
= average
of other students’ Rf values,
if available.
1. Rfvaluesarecalculatedratios
ofhowfaramoleculemovedupthepaperchromatographas comparedtothelengthofthesolventfront.Thesevaluesaretypicallyequivalentformultiple trials.Calculate your
Rf values based on your paper strip results, and record them inTable 1. The Rf value of the solvent front
will always = 1.0, since Rf is
a ratio.
2. Construct
a stacked bar graph to demonstrate how
the Rf value and the chlorophyll
pigment are related.They-axiswillrepresenttheRfscalefrom0.0to1.0.Onthebargraph,labelthe
calculated Rf with the name
of the associated chlorophyll pigment.
When complete, the bar graphshouldclosely
resembletheactualchromatograph.Include
astackedbargraphforyour results
plusanother stacked bar graphnext
to your
graphwith your classmates’
averaged
values.
Questions:
A. Identifytheareasofpigmentsthatyouobserveonthefilterpaper.Aretheylocatedinthe
order that you expected?
If not, why not?
B.
Compareyourpaperstripresultstotheresultsoftheradicchiopaperstripsbelow.Arethe
same pigments present
in radicchio leaves?
If not,
which chlorophyll pigments are missing?
How might you
have
guessed that this might be the case?
Example of Results Obtained from
Radicchio
Paper Chromatograph
Radicchio Paper Chromatograph,
dried and marked in preparationfor Chlorophyll Pigment
Rf determinations
Discussion
A. Was
the initialhypothesis supported or
refuted? Explain.
B. If you
do not see separate
bands of color on the filterpaper, what
might you conclude?
C. What
might explain why the separationof the colors occurred?
D. Howdoyourvaluescomparetoyourclassmates’valuesforthesamepigmentsonTable1and
in your graph? If they are not similar, what may be the reason?
Exercise2:ConversionofLightEnergytoFoodby
Plants
Questions
A. What
molecule was produced by
the Elodea while it was exposed to
light?
B. Which organelle(s) in the
plant cell is responsible for this reaction?
C. From
where was this molecule derived?
D. What
was the purpose of the light?
E. What molecule was produced by
the Elodea while it was wrapped in aluminum foil? F. Which organelle was
responsible for this reaction?
G. Setupatablesimilar
toDataTable3:ComparisonofPhotosynthieticRateintheLabReport
Assistantsection. CompareyourRateofPhotosynthesistotheaverageratesreportedbyother students in Table
3, if possible. How similar was your result
to theirs?
H. Nameatleastthreeexperimentalvariables
thatcouldexplainwhyyouroutcomemightvary
from that of other students or from
your own, if you repeated the experiment.
I. How
could one determine how much oxygen
is produced by the plant in one
hour?
1.
From
geometry,
recall
that Volume =?r2h,where r = inside radius
of a circle, or here the inside of the tube, and h = length of the movement, which means ? x radius squared
x height. Since the radius is ½ of the inside diameter, this equationis equivalent
to
= 3.1416 x (inside diameter of the bent tube in mm ÷ 2)2x height (equivalent
to the
distance
that the solutiontraveled)
= volume in mm3.
2. To convert mm3 volume to uL (typically the
volume specification used at
this level of measurement),
use
the
conversion
factor of 1
mm3 = 1
uL. Do
thecalculationtodetermine
thevolumeofoxygenthatisproducedbytheplantinone
hour.
3. How
long would the plant need to
photosynthesize to
produce one liter of O2?
Discussion
A. Did this experiment support or refute your
initialhypothesis. Explain.
B. Chlorophyll
gives plant leaves their green color, (or red,
in the case of radicchio,
since it lacks a pigment that
is typically present in green leaves). Research light
and color, and hypothesize whetherchlorophyllabsorbsgreenlighttoanyappreciableextent.Proposeanexperimentsimilar
to the one that you just performed
that could be used to
support your hypothesis.
C. There is current controversy as to
whether the atmosphere is warming due to the burningof fossil
fuelsandthe
destructionoftherainforests(the
GreenhouseEffect).Howdoesphotosynthesis and respirationrelate to
this controversy?
D. Why
are the tropics particularlyimportant
to oxygen
production?
Therefore,
why should you support actionsthat reduce
the cuttingof rainforests?
E. Whilethisexercisehasaddressedoxygenproduction,
what
otherimportantproductsresult
from
photosynthesis?Hint:Beside
theproduction ofoxygen,whyareallanimals
dependenton plants?
Exercise 3: Respirationin Plants
Questions
A. Why
is the Elodea rinsed in distilledwater?
B. What
gas did you add to the Bromothymol
blue solution?
How do you
know? Respirationis
our primary form of energy production.
C. Why
did the color turn more green-yellow or yellow when you
breathed
into it?
D. Write an equationfor
the reactionthat explains the color change.
E. Whatcolorchangeoccurred afteryouplacedtheElodeainthetesttubeandturnedthelight source
on/off?
F. What
gas is produced and responsible
for this change? G. What
gas is being removed?
H. What process
is occurring in the firsttrial
without the aluminum foil?
I. Whatdidyouobservewhenyourepeatedtheexercisewiththetesttubecontaining
the
Elodea wrapped in aluminum foil?
J. What gas is produced?
What term could be applied to the second
trial? K. Which process took
longer?
Why?
Discussion
A. HowdidthetimeforcolorchangevarybetweenwhentheElodeawaspresentinthetesttube
(trial
1) versus when the Elodea was
wrapped in aluminum foil? What
might explain this?
B. Why
do both plants and animals respire?
Would life in either group be possible without respiration?
C. Was
the initialhypothesis supported or
refuted? Explain.
D. HeatingcausesaBromothymolblueindicatorsolution
tochangefromyellowtobluevery rapidly
without a plant present.
What explains this reaction?Howdid you
control for
heat in this exercise?
E. SetupadatatablesimilartoDataTable5:ComparisonofPhotosyntheticRateintheLab
Report
Assistantsection.Compareyourresultstothoseofyourclassmates,ifavailable,inTable
5. Were
your results similar? What
trends do you observe
between
the two trials?
F. Explainwhyyourdatamayhavedifferedfromthatofotherstudents.Whatvariables
could explain this difference?
G. HowwouldyoubeabletochecktoensurethatitwastheElodeaplantthatfacilitatedthe
color change and not some other factor?
H. Howdoplants,suchasPinedrops,Pterosporaandromedea,ortheGhostPlant,Monotropa
uniflora,that are
not photosynthetic,make their food?
Do they respire?
Laboratory Summary
What have you
learned from doing this laboratory?
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