Question

what happened to the co₂ concentration when the plant was covered in foil? why?
in dark conditions: co2 level increases because only cellular respiration is being performed by the plants.
in dark conditions: co2 level decreases because only cellular respiration is being performed by the plants.
in dark conditions: co2 level increases because both metabolic pathways (cellular respiration and photosynthesis) are being performed by the plants.
in dark conditions: co2 level decreases because only photosynthesis is being performed by the plants.

Explanation:

Plants perform cellular respiration (which produces CO₂) in both light and dark. Photosynthesis (which consumes CO₂) occurs only in light. When covered in foil (dark), only cellular respiration happens, increasing CO₂.

Answer:

In dark conditions: CO2 level increases because only cellular respiration is being performed by the plants.