What factors affect rate of photosynthesis in a plant?

There are three key factors affecting rate of photosynthesis at GCSE level. They are light intensity, CO2 concentration, and temperature. These factors are best visualised by drawing graphs with rate of photosynthesis on the y-axis and the factor on the x-axis. As you can see, with light intensity and CO2 concentration, at first the rate increases but then it plateaus (flattens out). This is because another factor starts limiting the reaction. Temperature is different though, the rate of photosynthesis goes up but then actually goes down again at higher temperatures. This is because enzymes needed for photosynthesis reactions start to denature so they can't work properly.