Date ____
Elodea Lab
Name __________
Background Information:
Elodea is a common “exotic” aquarium plant that has also escaped into some local waterways.
Elodea is an excellent plant for our studies of photosynthesis and cells because it is easy to grow,
and readily available.
Recall that photosynthesis requires certain raw materials and produces certain products, one of
which is released by the cells as a gas. You have learned about the process of photosynthesis, and
now you will act as any scientist would and ask to see the proof! How can you see the proof
however, since gases are colorless and oxygen and carbon dioxide are both odorless too?
Problem: Is photosynthesis taking place in the aquatic plant Elodea?
Pre-lab Questions: (Read Procedure before answering.)
1. How and what will we measure to see if photosynthesis is taking place?
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2. Why would we use an aquatic plant for this experiment instead of a terrestrial plant?
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Materials: (per group)
Sprig of Elodea
Distilled Water w /Baking Soda,
Test Tube, ,
60 watt spotlight
Flask
Large Beaker
Timer or Watch
Metal Stand
Procedure: (Before you begin, create a data table.)
1. Fill a test tube and a flask with distilled water. Add 0.5 g. of
baking soda to each.
2. Cut the end of the sprig of Elodea.
3. GENTLY crush the freshly cut end.
4. Place the Elodea in a small flask. Place the flask in a large beaker
and cover with water.
5. While holding your thumb over the opening invert the tube over the
opening of the flask and secure with a clamp.
6. With the light off, observe the freshly cut end of Elodea. Count the number of oxygen
bubbles that are released in a minute. Record for each minute for 5 minutes.
7. Now place the Elodea in front of the light and turn it on. Wait a few minutes.
8. Over the next 5 minutes count the number of bubbles that are released each minute. Record
the results.
Date ____
Elodea Lab
Name __________
Data Table: Number of bubble produced by Elodea
1st min
2nd min
3rd min
4th min
5th min
Average
Light
Dark
Post-Lab Questions:
1. How many times more is the Elodea photosynthesizing in the light compared to the Elodea in
the dark. Use data to support your answer.
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2. How would you expect your results to change if you were to use a 200-watt light bulb instead
of a 100-watt light bulb?
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3. How would you expect your result to change if you were to use green light instead of white
light? Explain your answer.
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4. Why was baking soda added to the water? What is the gas emitted and from which reaction?
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5.
Write out the overall equation for photosynthesis and describe what role light plays in the
light reaction.
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6. Describe the exact location of the light reaction moving from the outside of a plant cell
toward the inside.
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