investigation into light and starch production
DESCRIPTION
Hypothesis: Materials: F : Highly Flammable Title: Investigation into Light and Starch Production IF sunlight is a necessary component of the photosynthetic reaction THEN plants placed in sunlight will produce starch and those placed in the dark will not. During Photosynthesis Propanol F : Mycket brandfarligt Lugol’s Solution A‐7TRANSCRIPT
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Title: Investigation into Light and Starch Production During Photosynthesis Purpose: The purpose of this investigation is to test one of the reactants needed in the photosynthetic reaction of plants Problem: How does changing the light conditions (light or 24 hrs. in darkness) affect the production of starch in plants. Hypothesis: IF sunlight is a necessary component of the photosynthetic reaction THEN plants placed in sunlight will produce starch and those placed in the dark will not. Materials:
o hot plate o propanol o beakers o tweezers o test tubes o Lugol’s solution o Green plant leafs
(light and dark)
Lugol’s Solution
Propanol
F : Mycket brandfarligt
F : Highly Flammable
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Procedure:
1) Collect leaves from the plants to be tested. One placed in direct sunlight and one left in the dark for 24 hours.
2) Pour some boiling water from a kettle into a large beaker.
3) Using tweezers pick up one of your leaves and place it in the hot water for about two minute.
4) Using tweezers, remove the leaf from the boiling water and note how it has changed.
5) Drop the leaf into a test tube and push it to the bottom with a glass rod.
6) Add enough propanol (ethanol in the picture below) to cover the leaf, and stand the test tube in your beaker of hot water, or in the hot water bath.
7) Watch as the ethanol boils and the green colouring (chlorophyll) is removed from the leaf. This will take a few minutes.
8) Replace the hot water with freshly-boiled water from the kettle after 5 minutes if there is still some green colour in the leaf.
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9) Using tweezers, remove the leaf from the boiling tube and rinse the leaf in cold water.
10) Put the leaf in a Petri dish on a white tile.
11) Add Lugol’s solution to the leaf from the dropper bottle. Make sure the leaf is completely covered with iodine.
m Watch for a few minutes to see if a blue-black colour develops in any part of the leaf. A blue-black colour with iodine solution indicates that starch is present.
n Wash your hands to remove any traces of plant sap, or the chemicals that you have used.