Photosynthesis and Respiration MargaretE.Vorndam,M.S

26 Jun Photosynthesis and Respiration MargaretE.Vorndam,M.S

Question
Photosynthesis and Respiration

MargaretE.Vorndam,M.S.

Version 42-0103-00-01

LAB REPORTASSISTANT

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

Distanceto top of pigment,mm

Rf

Other Students’Rf

Average

# of Rf Results Averagedfrom other Students(N)

Topof Solvent

Front

NA

Carotenoids

Xanthophylls

Chlorophylla

Chlorophyllb

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

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 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

Elodea, Bromothymolblue solutionin Foil

Data Table 5: Comparison of PhotosyntheticRate

My Result: Total timefor color

change,

T1– T0,minutes

Averageof Other Students’Results:

Total time for color change,

T1– T0,minutes

N= (numberof dataaveraged)

Elodea, Bromothymolblue solution

Elodea, Bromothymolblue solutionin Foil

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?

.0/msohtmlclip1/01/clip_image002.jpg”>B. Compareyourpaperstripresults totheresults oftheradicchiopaper strips below. Are the same pigments present in radicchio leaves?

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. Nameatleastthreeexperimentalvariablesthatcouldexplainwhyyouroutcomemightvary 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?

.0/msohtmlclip1/01/clip_image004.gif”>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. Thereiscurrentcontroversyastowhethertheatmosphereiswarmingduetotheburning 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. 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 afteryouplaced theelodeainthetesttubeandturnedthelight 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

ReportAssistantsection. 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?

LABORATORYSUMMARY

What have you learned from doing this laboratory?