Final answer:
Light and CO2 availability are directly proportional to the amount of O2 produced through photosynthesis; increased levels of both result in higher O2 production. However, when plants close stomata, CO2 uptake is limited, leading to reduced photosynthesis and O2 output.
Step-by-step explanation:
The availability of light and carbon dioxide (CO2) significantly impacts the rate of photosynthesis, and hence, the production of oxygen (O2). An increase in both light intensity and the concentration of CO2 leads to an increased production of O2, as photosynthesis is enhanced under these favorable conditions. In contrast, a hot, dry day can cause plants to close their stomata to conserve water, which in turn limits the entry of CO2 into the leaf and thereby inhibits the rate of photosynthesis, leading to reduced O2 output.When plants close their stomata, it will affect the concentration of gases within the leaf. The levels of O2 are likely to increase inside the leaf, while CO2 will decrease due to it being used up in the Calvin cycle. This leads to a potential buildup of O2 and a deficit of CO2, slowing down the photosynthetic process, including the Calvin cycle, where CO2 is fixed into organic molecules like sugars/carbohydrates.To conclude, the main answer to how light and CO2 availability affect O2 production is a) Increased light and CO2 lead to increased O2 production. However, when plants close their stomata to conserve water, this limits the entry of CO2 and subsequently inhibits photosynthesis, which would reduce O2 production.