Final answer:
Light intensity decreases with the square of the distance from the light source, affecting photosynthesis. Excessive light intensity can cause photoinhibition, impairing photosynthesis. Increased CO2 diffusion can enhance photosynthesis if other factors are adequate.
Step-by-step explanation:
The distance from the light source affects the rate of photosynthesis as the amount of light energy available to plants decreases with increasing distance. This relationship is described by the inverse square law, which states that light intensity is inversely proportional to the square of the distance from the source. Consequently, if a plant is twice as far from a light source, it will receive four times less light, which significantly reduces the light energy available for photosynthesis.
Regarding the claim that there is an upper limit on the intensity of light usable for algae growth, excessive light intensity can lead to photoinhibition, a condition where the light-dependent reactions of photosynthesis are impaired, slowing down the overall photosynthetic rate and potentially harming the plant tissue.
If CO2 levels increase due to higher temperatures and faster diffusion rates, a plant might use the available CO2 more effectively for photosynthesis if light and water are not limiting factors. However, an excessive increase in temperature might also cause the plant to lose CO2 at a rate that could limit photosynthesis.