Final answer:
Cells become less efficient as they increase in size because the surface area-to-volume ratio decreases.
Step-by-step explanation:
Cells become less efficient as they increase in size because the surface area-to-volume ratio decreases. This means that the surface area of the cell does not increase at the same rate as its volume. As a result, large cells may struggle to exchange nutrients and wastes with their environment. For example, a spherical cell with a diameter of 5 µm would have a larger surface area-to-volume ratio compared to a cubed-shaped cell with a side length of 7 μm, making it more efficient in exchanging nutrients and wastes.