Tuesday, December 7, 2010

Photosynthesis "Dry Lab"

Materials Required for Lab
  • Water
  • Bromothymol blue (BTB)
  • 4 Straws
  • Aquarium snails
  • Elodeas (aquarium plant)
  • 4 beakers
You will need a light source and a dark space.

To observe Photosynthesis. 

  1. Fill the 4 beakers with water. Add BTB to one. Insert the straw and blow through straw to create bubbles. Observe the reaction (Carbon dioxide from exhaled breath and water creates carbonic acid, which causes a change in color.)
  2. Move to next beaker and add BTB. Add the aquarium snail. The snail will replace the straw's function. Observe reaction. (BTB turns yellow when exposed to acid.)
  3. To another beaker, add BTB and elodea, the plant will act like the snail and straw. Observe reaction. (Green plants photosynthesize in the light and respire all the time.)
  4. Use last beaker. Add BTB, snail, elodea. Observe in light. Put in dark for 3 hours and take out to observe if any changes have taken place. (BTB changes to a yellow color when exposed to acid and back to blue-green when returned to neutral pH.)
  1. What happens when you blow through the straw? Why?
  2. What do plants need to photosynthesize?
  3. What does carbon dioxide yield when chlorophyll and sunlight are present?

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