Volume+Surface+Area+Ratio+HC

The rate of exchange of materials and energy is a function of the cell's surface area

The rates of heate production, waste production, and resource consumption are functions of the cell's volume

The surface area to volume ratio decreases with an increase in cell size.

The volume to surface area ratio limits size because as the cell must be big enough to contain all the required organelles and to acomplish its function, but still absorb all the nutrients it needs. If the cell is too big, it does not have enough surface area to obtain all the nutrients.