Final answer:
When a leaf is exposed to light, it consumes CO₂ and produces O₂, which decreases the CO₂ concentration and increases the solution's pH, causing the hydrogen carbonate indicator to turn blue. Higher temperatures lead to faster CO₂ diffusion, potentially affecting the Calvin cycle and photosynthesis rate.
Step-by-step explanation:
A hydrogen carbonate indicator is used to show the effect of light on the net gas exchange from a leaf. This indicator changes color in response to pH changes, which are influenced by the concentration of carbon dioxide (CO₂) in the solution.
When a leaf undergoes photosynthesis in the light, it consumes CO₂ and produces oxygen (O₂). This leads to a decrease in CO₂ concentration, thereby increasing the pH of the solution and causing the hydrogen carbonate indicator to turn blue, due to the more alkaline conditions.
Hence, in the presence of adequate water and light for photosynthesis, if the leaf loses CO₂ at an increased rate due to higher temperatures facilitating faster diffusion, the Calvin cycle could be affected. This would result in a slowing down or possible stopping of photosynthesis if the carbon to be fixed in the system is inadequate.