Internal Factors

Internally, the presence of chlorophyll is essential for photosynthesis to happen at all, but the rate of photosynthesis is not strictly proportional to how much chlorophyll is present — because chlorophyll functions essentially as a biocatalyst, only a comparatively small quantity of it is needed to keep a much larger bulk of reacting raw materials turning over. Sugar, the end product of photosynthesis, itself becomes a limiting influence once it starts accumulating in the cell, slowing the process down as it builds up. A number of structural features of the leaf also play a role: the thickness of the cuticle and epidermis, the size and distribution of intercellular air spaces, the distribution of stomata, and how well-developed the chlo …