To determine whether photosynthesis or cellular respiration is occurring in a sealed chamber with an organism, scientists can measure the levels of oxygen (O₂) and carbon dioxide (CO₂) in the chamber over time. Here’s how they can interpret the data:
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Photosynthesis: This process occurs in plants and some microorganisms and involves the conversion of carbon dioxide and water into glucose and oxygen, using sunlight as the energy source. The general equation for photosynthesis is:
\[ \text{6 CO}_2 + \text{6 H}_2\text{O} \xrightarrow{\text{light}} \text{C}6\text{H}{12}\text{O}_6 + \text{6 O}_2 \]
- Indicators of Photosynthesis:
- A decrease in CO₂ levels: As the organism takes in CO₂ for photosynthesis, the amount of CO₂ in the chamber should decrease.
- An increase in O₂ levels: As a byproduct of photosynthesis, O₂ is released into the chamber, resulting in an increase in O₂ concentration.
- Indicators of Photosynthesis:
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Cellular Respiration: This process occurs in both plants and animals and involves the breakdown of glucose and oxygen to produce carbon dioxide, water, and energy. The general equation for cellular respiration is:
\[ \text{C}6\text{H}{12}\text{O}_6 + \text{6 O}_2 \rightarrow \text{6 CO}_2 + \text{6 H}_2\text{O} + \text{energy} \]
- Indicators of Cellular Respiration:
- An increase in CO₂ levels: As glucose is metabolized, CO₂ is produced, leading to an increase in CO₂ concentration in the chamber.
- A decrease in O₂ levels: O₂ is consumed during cellular respiration, resulting in a decrease in O₂ concentration.
- Indicators of Cellular Respiration:
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Overall Interpretation:
- If the measurements show decreased CO₂ and increased O₂, photosynthesis is likely occurring.
- If the measurements show increased CO₂ and decreased O₂, cellular respiration is likely occurring.
- If both processes can occur (as in plants that can photosynthesize during the day and respire at night), time of day can also play a crucial role in interpreting the results.
By continuously monitoring and recording the changes in gas concentrations, scientists can determine the predominant process taking place in the chamber at any given time.
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