Name:____________________________
IScS - Biology
Lab Activity: Elodea Oxygen (O2) Production
Objective:
In this lab, we will observe the creation of oxygen gas (O2) from Elodea plants by means of
photosynthesis.
Student Materials:
 4- small (15x150 mm) test tubes
 4- large (25x150 mm) test tubes
 Test tube rack
 Fresh Elodea stems
 Desk lamp or sunlit window
 Labeling tape
 Forceps
 Ruler
Student Procedure:
1) Work in pairs to prepare the following treatments (each pair makes four treatments):
a) with bicarbonate – shade
b) with bicarbonate – light
c) without bicarbonate – shade
d) without bicarbonate – light
2) Label the outside of your large test tube with your initials and your treatment groups.
3) Obtain a piece of Elodea 8cm in length.
4) Place your cut specimen into the smaller test tube such that the tops of the leaves are facing
towards the test tube opening.
5) Submerge both test tubes into a washtub station and gently jostle test tubes to remove all air
bubbles from within the tubes.
6) With both the large and small test tubes underwater, slide the smaller test tube upside-down
inside the larger one. Be sure there are not any air bubbles trapped inside the inner test tube
and remove the test tubes from the water station. Oxygen is released from the bottom side of
the leaves which is why you want your leaves upside-down within your experimental
chamber.
7) Place your plants in the appropriate light source. We will measure O2 production later in the
day.
8) Gently tap or shake the test tube so that all the bubbles that collected on the plant rise to the
top of your inner test tube. Then measure the size of the oxygen bubble that has been
produced by your plant (height and width measured in mm), calculate the volumes of the
bubbles and enter your group’s data in the class dataset (on the front board).
9) Make sure to copy the data for the whole class in your student worksheets before you leave.
Clean up:
1) Throw the Elodea sp. away in the Elodea sp. solid waste container. Bicarbonate water waste
goes in the bicarbonate liquid waste container. DI water may go down the drain.
2) Remove all labeling tape from the test tubes and rinse with DI water.
3) Place the test tubes upside down in the test tube racks on paper towels at the drying area.
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