Photosynthesis Lab Write Up

Materials:
     Bromothymol blue
     2 aquarium snails
     2 elodea (aquarium plant)
     pond water
     4 beakers
     light lamp

Procedure:
     1. Take all of the beakers and fill them 3/4 the way with pond water.
     2. Take all of the beakers and mix bromothymol blue with the water until you see a color change. Record your results.
     3. Take a beaker with bromothymol blue and water mixed in and place the snail into the beaker until you see a color change. Record your results.
     4. Take the third beaker with bromothymol blue and water mixed in and place elodea in the beaker. Place the beaker under the lamp for three hours. Record the color change.
     5. Take the last beaker with bromothymol blue and water mixed in, and place a snail and a elodea in the water. Leave in the light for three hours. Record the color change in the light.
     6. Take the beaker from step 5 and place in it in the dark for three hours. Record the color change.
     7. Clean up, return the snails to the wild, and DON'T DRINK THE POND WATER!

Observation/Conclusion:
     1. Water plus bromothymol blue is blue green - because the water is a neutral pH.
     2. Water plus bromothymol blue plus an aquarium snail turns yellow - because the snail produces carbon acid and BTB turns yellow in acid.
     3. Water plus bromothymol blue plus elodea, is blue-green in light. -green plants photosynthesize in the light and respire all the time, but still keeping the pH neutral, allowing the water and BTB to remain blue-green.
     4. Water plus bromothymol blue plus a snail plus elodea is blue-green in light and yellow when left in the dark for three hours. - because the carbon dioxide produced by the snail is soaked up by the elodea due to photosynthesis, allowing the water to remain blue-green in light. But, because in the dark, the elodea can't photosynthesize, the carbon dioxide from the snail turns the water acidic, making the water turn yellow when in the dark.