Solved by a verified expert:Photosynthesis and Respiration
Version 42-0103-00-01
Observations
Data
Table 1: Rf Value Comparison for Chlorophyll Pigments
Chlorophyll
Pigment
Observed
Color
Distanceto top of
pigment,mm
Rf
Other
Students’Rf
Average
# of Rf Results
Averagedfrom
other Students(N)
Topof
Solvent
Front
NA
20mm
Carotenoids
Yellowish
20mm
Xanthophylls
Greenish Yellow
10mm
Chlorophylla
Greenish
30mm
Chlorophyllb
Green
20mm
Distancetotopofpigment,mm:Measurefromwherethetopofthesolventextractlevel
intersectedthepaperchromatographtothetopmostlevelofthecolor.Thenmeasurethis
distance
to the top of the solvent front and record.
Data
Table 2: Gross Photosynthesis
in Elodea
Rates
Distanceof travel,mm
Net Photosynthesis
Rate
over
10 minutes
= mm of movement from
marked beginning point on bent
tube to end point after10
minutes
20mm
RespirationRate
over
10 minutes
= mm of movement from
marked end point on bent
tube
toward beginning point after10 minutes
26mm
Gross Photosynthesis
over
10 minutes
(= mm Net Photosynthesis
+ mm Respiration)*
20+26=46mm
Rate
of Photosynthesis over
one hour
(= Gross Photosynthesis
÷ 10 minutes x 60 minutes)
46/10×60=276mm
*Was respirationoccurring during photosynthesis? Add back the O2 that was
consumed by
plant respirationto
obtain
the total photosyntheticrate.
Data
Table 3: Comparison of PhotosyntheticRate
My PhotosyntheticRate Result
Average of Other Students’ PhotosyntheticRate
Results
N=
(numberof dataaveraged)
Data
Table 4: Observationof pH Change in the Oxygen
Cycle
Contentsof
Respirometer
Initial
Color
T0, minutes
Final
Color
T1,minutes
Total timefor color
change,
T1– T0,minutes
Elodea,
Bromothymolblue
solution
Green
9 minutes
Blue
16 minutes
16-9=5
Elodea, Bromothymolblue
solutionin Foil
Blue
18
BLUE
51
51-18=33
Data
Table 5: Comparison of PhotosyntheticRate
My Result: Total
timefor color
change,
T1– T0,minutes
Averageof
Other Students’Results:
Total
timefor color change,
T1– T0,minutes
N=
(numberof dataaveraged)
Elodea, Bromothymolblue solution
16-9=5
Elodea, Bromothymolblue solutionin Foil
51-18=33
Exercise 1:
ChlorophyllPigments
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. Compareyourpaperstripresults
totheresults
oftheradicchiopaper strips below. Are
the same pigments present
in radicchio leaves?
No
If not, which
chlorophyll pigments are missing?
How might
you have guessed that this might be the case?
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
Assistant section. Compare
your Rate of Photosynthesis to
the average rates
reported by other 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 =
Pr2h,
where
r=
insideradius
ofacircle,orheretheinside
ofthetube,and h = length of the movement, which means pi x radius squared x height.Sincetheradiusis½oftheinsidediameter, this
equation isequivalent to= 3.1416 x (insidediameter ofthe
bent tubein mm÷2)2
xheight(equivalenttothedistancethatthesolution
traveled) = 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.
Thereiscurrentcontroversyastowhethertheatmosphereiswarming
duetotheburning offossilfuelsandthedestruction oftherainforests(i.e.,theGreenhouse
Effect). Howdoes photosynthesis
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. SetupadatatablesimilartoDataTable5:ComparisonofPhotosyntheticRate,intheLab
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?
LaboratorySummary
What have you
learned from doing this laboratory?
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