Question

What single factor limits the size that most cells are able to attain?

Answer 1

The cell varies in shape and size, it ranges from as small as 3-30 micrometre to a large size of about 150 millimetres, similar to the size of an ostrich egg. The cell remains smaller in size to maintain the ratio between the fluid and plasma membrane present in them.

Complete answer:
The single factor that limits the size of most of the cell is the surface volume ratio.
The size of the cell gets limited by the nucleo-cytoplasmic ratio, which determines the range of control of metabolic ratio and the ratio of surface to volume. The metabolically active cells remain smaller in size due to high nucleus- cytoplasmic content and high surface area- volume. The nucleo-cytoplasmic ratio helps to control the metabolic activity whereas the surface-area volume ratio allows the exchange of material between the cell and the outer environment. An increase in cell volume leads to a smaller expansion in the surface area of the cell and an increase in the size of the cell decreases the surface area to volume ratio which makes the cell less efficient.

Additional Information:
Cells show a variety of shapes, it may be disc-like, polygonal, rectangular, cuboidal, etc. The factors which control the shape of RBC are their function, position, exoskeleton or exoskeleton, cell wall, mutual compression, age and viscosity.

Note:
Every cell has a different life span therefore the old and weak cells die and are over replaced by the new cell. The new cell forms a younger cell by division and the formation of new cells from the pre-existing cell continues till the life of a cell.