Students see photosynthesis in action
Seventh grade students hit the lab and saw photosynthesis in action.
Their goal was to explore the relationship between cellular respiration and photosynthesis using pH indicator bromothymol blue and the aquatic Elodea plant.
Their goal was to explore the relationship between cellular respiration and photosynthesis using pH indicator bromothymol blue and the aquatic Elodea plant.
After putting on safety goggles, gloves and aprons, the students were ready!
Middle school teacher Ellen Alt placed a few drops of bromothymol blue into two cups containing water. Students blew into the bromothymol blue solutions. Once the carbon dioxide from their lungs mixed with the water solution, it turned from blue to yellow (slightly acidic and causing the color change).
One sprig from the Elodea plant was then placed in the yellow solution with one cup being placed in a windowsill and another covered in aluminum foil.
The cup on the windowsill then turned back to blue as the Elodea performed photosynthesis and oxygen was released (slightly basic acid causing it to turn back to blue). The cups covered in foil respired and released carbon dioxide, which when mixed with water formed carbonic acid and lowered the pH, causing it to remain yellow.
Students then compared the Elodea samples on a microscope slide where they observed the plant cells and its organelles--primarily cell walls, cytoplasm and chloroplasts.
“I thought that the lab was very fun, and I loved that I was able to have a better understanding of photosynthesis,” said Luke Hahne ’26.
“It showed how plants release oxygen while going through photosynthesis, making the bromothymol blue turn blue. What surprised me most was how fast the elodea changed the water blue/green from yellow.”
Next up: Cellular respiration!
OCT272020
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Middle school teacher Ellen Alt placed a few drops of bromothymol blue into two cups containing water. Students blew into the bromothymol blue solutions. Once the carbon dioxide from their lungs mixed with the water solution, it turned from blue to yellow (slightly acidic and causing the color change).
One sprig from the Elodea plant was then placed in the yellow solution with one cup being placed in a windowsill and another covered in aluminum foil.
The cup on the windowsill then turned back to blue as the Elodea performed photosynthesis and oxygen was released (slightly basic acid causing it to turn back to blue). The cups covered in foil respired and released carbon dioxide, which when mixed with water formed carbonic acid and lowered the pH, causing it to remain yellow.
Students then compared the Elodea samples on a microscope slide where they observed the plant cells and its organelles--primarily cell walls, cytoplasm and chloroplasts.
“I thought that the lab was very fun, and I loved that I was able to have a better understanding of photosynthesis,” said Luke Hahne ’26.
“It showed how plants release oxygen while going through photosynthesis, making the bromothymol blue turn blue. What surprised me most was how fast the elodea changed the water blue/green from yellow.”
Next up: Cellular respiration!
OCT272020
