Solved by a verified expert:Photosynthesis and Respiration
Margaret
E. Vorndam, M.S.
Version42-0103-00-01
Lab Report Assistant
Thisdocumentisnotmeanttobeasubstitute
for
aformallaboratoryreport.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
Carotenoids
Xanthophylls
Chlorophyll
a
Chlorophyll
b
Distancetotopofpigment,mm:Measurefromwherethetopofthesolventextractlevel
intersectedthepaper
chromatographtothetopmostlevelofthecolor.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. Compareyourpaperstripresultstotheresultsoftheradicchio
paperstripsbelow.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?
P.
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?
F. Which organelle was
responsible for this reaction?
G. SetupatablesimilartoDataTable3:ComparisonofPhotosyntheticRateintheLabReport
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. While
thisexercisehasaddressedoxygenproduction,
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. Whatdidyouobservewhenyourepeatedtheexercisewiththetesttubecontainingthe
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. Setupadatatablesimilar
toDataTable5:ComparisonofPhotosyntheticRateintheLabReportAssistantsection.Compareyourresultstothoseofyourclassmates,ifavailable,inTable
5. Were your results similar? What trends do you observe
between
the two trials?
F. Explainwhyyourdatamayhavedifferedfromthatofotherstudents.Whatvariablescould
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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