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Examine the example table to the right and answer the question that follows:

Content of Test Tube Color When Left in Light Color When Left in Dark
1. Baking soda + BTB Yellow Yellow
2. Baking soda, BTB, and Elodea Green Greenish yellow
3. Baking soda, BTB, and Elodea Green Yellow

Which trial performed photosynthesis when left in the light? Which trial performed photosynthesis when left in the dark?

1 answer

To determine which trials performed photosynthesis, we can analyze the content and color changes in light versus dark conditions.

  1. Trial 1: Baking soda + BTB

    • Color When Left in Light: Yellow
    • Color When Left in Dark: Yellow
    • Conclusion: No photosynthesis, as the color remains yellow in both light and dark. Yellow indicates the presence of carbonic acid, suggesting no net uptake of carbon dioxide.

  2. Trial 2: Baking soda, BTB, and Elodea

    • Color When Left in Light: Green
    • Color When Left in Dark: Greenish yellow
    • Conclusion: This trial performed photosynthesis when left in the light (green indicates a balanced pH with some uptake of CO2) and possibly continued some metabolism in the dark but produced less than when in light (the greenish yellow indicates some CO2 production).

  3. Trial 3: Baking soda, BTB, and Elodea

    • Color When Left in Light: Green
    • Color When Left in Dark: Yellow
    • Conclusion: This trial also performed photosynthesis in light (green signifies some uptake of CO2) but did not perform photosynthesis in the dark, as indicated by the change to yellow, showing CO2 was not being consumed.

Summary:

  • Photosynthesis in Light: Trials 2 and 3 (both produced green)
  • Photosynthesis in Dark: None of the trials performed photosynthesis in the dark since trial 3 turned yellow, indicating a lack of CO2 uptake.