What primarily limits how big a cell can grow?

The primary factor that limits how big a cell can grow is the surface area-to-volume ratio. As a cell increases in size, its volume grows much faster than its surface area. This relationship is crucial because the surface area of the cell membrane is where exchange of materials (such as nutrients and waste products) occurs. A larger volume requires more resources and produces more waste, but if the surface area is not sufficiently large to accommodate these demands, the cell will not function efficiently.

When the surface area becomes too small relative to the volume, it can lead to factors such as inadequate intake of essential nutrients and inefficient removal of waste, ultimately affecting cell health and function. Thus, even though cells may have the genetic information necessary to grow larger and have energy available, it is the limitations imposed by the surface area relative to volume that ultimately restricts cell size and functionality.