In their natural environment, leaves of plants are exposed to rapid changes in light intensity, due to clouds, wind and shading from other leaves. This thesis addresses the issue of how fast leaf photosynthesis responds to changes in light intensity and what are the molecular mechanisms involved in these responses. In addition to experiments with Arabidopsis thaliana, simulation models were built to emulate the responses of leaves. These models are useful to make predictions, design better plants and gain insights into how specific reactions determine the behaviour of photosynthesis at the molecular and leaf level. This thesis identifies a series of mechanisms that could be manipulated to enhance photosynthesis and provides an in silico platform for future research.