Final answer:
As a cell increases in size, its volume grows more significantly than its surface area, limiting diffusion efficiency due to a decreased surface area-to-volume ratio. Large cells may struggle with nutrient and waste exchange, indicating why cell size is limited and why cells must develop adaptations for efficient transport.
Step-by-step explanation:
As a cell becomes bigger, its volume grows much more than its surface area, which makes diffusion of substances into and out of the cell proceed at an inadequate rate.
This is due to the fact that as a cell's size increases, the distance that substances must travel becomes greater, slowing the diffusion rate.
This places a limitation on the maximum size of a cell. For example, a large spherical cell will face difficulties because nutrients or waste cannot efficiently reach or depart from the cell's center, making it essential for cells to remain small or develop adaptations for efficient transport.
If the cell grows too large, the plasma membrane won't have sufficient surface area to support the rate of diffusion required for the increased volume.
This results in a decrease in the cell's surface area-to-volume ratio as it grows, leading to decreased efficiency in transport across the cell membrane.
Cells respond to this challenge by dividing, developing organelles for specific tasks, or evolving other structural adaptations to enhance cellular transport, as seen in eukaryotic cells with more sophistication than prokaryotic cells.