Wondered Why Cells Don't Grow After A Particular Size? Answer : The concept of surface area to volume ratio... Surface area to volume ratio is an important concept to understand the limitation of cell size. One of the reasons limiting cell size growth is the metabolic rate and the exchange of excretory products. Curious what metabolism has got to do with cell size? It is all that plays the role of growth within cells. Metabolism is a chemical breakdown of biomolecules to produce energy, during this reaction the build up of metabolic waste accumulates within the cells. In order to prevent accumulation the cell tents to excretes waste, hence this means there must be a larger surface area for faster rate of excretion. Volume on the other is proportional to the cell metabolic rate. Hence the relation of metabolic rate with volume and surface area is of key significants for a proper working of a cell. This could be seen in the following figure. (Source : Blood - GCSE Biology (Sin