Question

connection to phenomena
the plants in davids jar are doing photosynthesis. co₂ and h₂o were not regularly added to his jar, but the plants continued to do photosynthesis. how is this possible?

Explanation:

In a closed - system like the jar, there is a cycle of substances. Respiration by the plants produces CO₂ and water is recycled through processes like transpiration and condensation within the jar. Also, the initial amount of CO₂ and water present may be sufficient for a period of time for the plants to continue photosynthesis.

Answer:

There is a cycle of substances within the closed - jar system including CO₂ and water, and the initial amounts may sustain photosynthesis for a while.