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Photosynthesis Science Fair Project

Photosynthesis and Starch

Photosynthesis and Starch | Science Fair Projects | STEM Projects
We'll be testing how carbon dioxide affects the amount of starch in a leaf of a geranium plant. We'll measure the amount of starch left in a leaf of a geranium plant under three conditions: carbon dioxide increased, decreased, and neither increased or decreased.


The hypothesis is that increased photosynthesis increases the starch in the green plant.

Method & Materials

You will mark three geranium plants, put them in bags with different materials, and place them in the sun for one day. After one day, you will break off one leaf from each plant and put it in a Petri dish. You will then put the leaf in a beaker with hot alcohol and observe the color change of the three leaves.
You will need three geranium plants, three 2 gallon plastic bags with twist to close, two 250ml Beakers, one 500ml Beaker, one Hot Plate, one Pair of Plastic Tongues, four Petri Dishes, one 1pt. 91% Isopropyl Alcohol, one Package of Alka-Seltzer, one 50mL of Soda Lime, one Bottle of Potassium Iodide, three Pieces of Cardboard, one Pitcher of Water.


The results of the experiment showed that the amount of starch in the leaf of the geranium plant was affected by the amount of carbon dioxide present. The leaf with increased carbon dioxide had the most starch, while the leaf with lower carbon dioxide had the least starch.

Why do this project?

This science project is interesting and unique because it explores how carbon dioxide affects the amount of starch in a leaf of a geranium plant.

Also Consider

Variations to consider include testing different plants and shielding parts of the leaf from the sun.

Full project details

You can find additional information and details for this science fair project here. Have fun exploring!

Related video

Hey there! Here are some awesome videos about this science project that we think you'll really like. They're not only super fun, but they'll also help you learn more about the science behind the project. So sit back, relax, and get ready to have some fun!!
This video provides a clear demonstration how to detect the presence of starch in a leaf.
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