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Spotting a Leak in a Plant Gas Chamber 4 questions
Spotting a Leak in a Plant Gas Chamber
Base your answers on the information provided and your knowledge of chemistry. Use the 2025 Chemistry Reference Tables as needed.
A class uses chambers to measure carbon dioxide in the air around a plant. It compares readings taken ten minutes apart. In an illuminated sealed chamber, a decline can indicate that the plant removes more CO2 by photosynthesis than it releases through respiration. The class also runs a chamber with no plant as a blank.
| Chamber | Initial CO2 (ppm) | CO2 after ten minutes (ppm) |
|---|---|---|
| Plant, lid sealed | 650 | 570 |
| No plant, lid sealed | 650 | 650 |
| No plant, lid unlatched | 650 | 590 |
Question 1
What does the no-plant, sealed trial show about the meter readings under the test conditions?
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Question 2
Calculate the average change per minute in CO₂ concentration for the sealed plant chamber. Include the sign.
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A student tests a plant in a chamber with an unlatched lid. The CO2 reading drops from 650 to 610 ppm in ten minutes. The student argues that this reading by itself demonstrates net CO2 uptake by that plant.
Question 3
Which result shows why the new reading alone cannot demonstrate that claim?
- CO₂ fell in the no-plant chamber with an unlatched lid.
- CO₂ stayed the same in the no-plant chamber with a sealed lid.
- All chambers began at the same measured concentration.
- CO₂ fell in the sealed plant chamber.
Question 4
Propose a fair comparison to test whether changing light level affects net CO₂ uptake by the same plant. Identify what to measure and one condition besides the plant to hold constant.
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