ElodeaPhotosynthesisLab

Problem:To what extent does the light source affect the rate of photosynthesisinElodeawaterplants? (Light Source Options: Natural, Artificial White, Red, Green, Purple, and No Light)

Research:1)Whatis theequationforphotosynthesis?

2)WheredoplantgettheCO2forthisprocess(whatorganismsreleasethisgas)?

3)Whatorganelleinplantsisresponsibleforphotosynthesis(producingfood)?

4)Whatisthepigmentfoundinthisorganellethatabsorbslighttopowerphotosynthesis?

5)Ifaplantwereunderwaterandwasphotosynthesizing,whatgaswouldbevisiblybubbling fromtheplant?

Hypothesize: Which light source do you think will cause the Elodea to produce the most Oxygen? The least?

Which COLORED light source will cause the Elodea to produce the most oxygen? The least? WHY?

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PARTA.SettingUptheExperiment

1.ObtainagreensprigofElodea.Removeseveralleavesfromaroundthecutend ofthestem.Sliceoffaportionofthestematanangleandlightlycrushthecutendofthestem.

2.Placetheplantintothetesttube,stem end down

3.Filledthetest tubewithwatersothattheplant iscompletelysubmersed.

4.Label your test tube with your group and class period using masking tape!

PARTB.RunningtheExperiment

1.Place your elodea in your chosen light source

2.Leave 45 minutes

3.Retrieve your test tube

4.Add 3 drops of Bromothymol Blue to your tube

5.Gently stir the BTB into your tube

6.What color did the BTB turn? Record your data on the table on the back of this page.

7.Once you have your data, retrieve data from other groups about the amount of bubbles produced under each light source.

8.Prepareagraphof yourresults.TheX-axiswillbethe color of the lightandtheY-axiswillbethe amount of Oxygen produced.

DataTable:

COLOR OF LIGHT SOURCE / AMOUNT OF OXYGEN
Natural Sunlight
Artificial White Light
Red Light
Green Light
Purple Light
No Light

Graph(bar):

1)Didyourdatasupportyourhypothesis?Explain.

2)Whatwentwellwiththeexperiment?

3)Whatwentwrongwiththeexperiment?

4)Whatnewproblems(questionsforstudy)aroseasyoudidthisexperiment?

5)BONUS!Bromothymol Blue or BTB turns blue in the presence of oxygen and yellow in the presence of Carbon Dioxide. Now that your BTB has turned into a specific color, how could YOU turn it the other color? Propose your idea to Coach Berg. He may let you try it!