With water, light energy from the sun, and carbon dioxide from the air, photosynthetic organisms are able to build simple sugars. Organisms that can make their own food are called autotrophs , and are at the base of the food chain. The basic reaction is:.
Oxygen molecules are colored to show their fate. Oxygen from CO 2 ends up in glucose. Oxygen from water becomes free O 2. Photosynthesis has two stages. Measure content performance. Develop and improve products. List of Partners vendors. Share Flipboard Email. Anne Marie Helmenstine, Ph. Chemistry Expert. Helmenstine holds a Ph. She has taught science courses at the high school, college, and graduate levels.
Facebook Facebook Twitter Twitter. Featured Video. Cite this Article Format. Helmenstine, Anne Marie, Ph. Scale, Proportion, and Quantity. Structure and Function. Stability and Change. Video Demonstration. Baking soda sodium bicarbonate Gram scale Water Liquid dish soap Spoon or other implement for mixing solution Soda straw or hole punch Spinach leaves or ivy leaves mL syringe without a needle Clear plastic cup 1-cup size or mL beaker Incandescent or watt equivalent lightbulb in fixture preferably with a clamp Timer Notepaper and pencil or similar to record results Optional: ring stand, foil, thermometer, ice, hot water, colored gel filters.
Make a 0. Add a few drops of liquid dish soap to this solution and mix gently, trying to avoid making suds in the solution. Using the straw or hole punch, cut out 10 circles from your leaves see photos below. Straws work best with spinach; hole punches work best with ivy. Remove the plunger from the syringe, and remove the cover from the tip, if there is one.
Put the leaf disks into the barrel of the syringe, and tap them down to the tip. If you have a straw, you can blow the discs gently into the plunger see photos below. Replace the plunger into the syringe, being careful not to touch or damage the leaf disks see photo below.
Pour mL of bicarbonate solution into the cup. Try to avoid making suds. Draw about 6—8 mL of bicarbonate solution into the syringe. The leaf disks should float in the solution see photos below. Hold the syringe with the tip up, and expel the air by gently pushing on the plunger. Plug the tip of the syringe tightly with your finger, and gently pull on the plunger, creating a slight vacuum.
You should see tiny bubbles coming out of the leaf disks. Hold the vacuum for a few seconds, and then release the plunger, letting it snap back see photos below. Some of the disks should begin to sink. Repeat the previous step several times, until all of the disks have sunk to the bottom of the solution see photo below. You may need to tap on the plunger to release the bubbles in order to make all the leaf disks sink.
When all the leaf disks have settled to the bottom of the solution, carefully remove the plunger and pour the disks and solution into the cup. They should settle to the bottom of the cup see photos below. If any leaf disks float, remove them from the beaker.
Set up your light fixture so that it is suspended about 12 inches 30 cm above the table. You may want to use a ring stand for this.
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