surface area: the rate of exchange of materials into and out of the cell is a function of the surface area.
volume:the metabolism of the cell (the chemical processes occurring within a living cell or organism that are necessary for the maintenance of life) is a function of the volume. Metabolism includes heat production/waste production/resource consumption of a cel.
therefore: as the dimensions of a cell increase, V increases proportionally faster than SA thus, SA/V ratio decreases with cell size setting an upper limit on cell size. Lower relative SA reduces rate of exchange while higher relative V increases metabolic demands thus, rate of exchange can’t meet needs of metabolic demands. The cell (usually) will either divide into two smaller cells or may die.
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