Biology - Surface Area to Volume Ratio
Surface Area to Volume Ratio
Cells absorb useful substances and rid themselves of wastes through their
surface. The surface area of a cell determines the rate at which substances
can enter and leave the cell. In other words, the surface area determines
the rate of supply of necessary materials and the rate of waste removal.
The resources on this page will help you to explore this idea further.
View the video of a skyscraper. It has a higher surface area to volume
ratio than a sphere, but not as high as that of a leaf.
A sphere has a lower surface area to volume ratio than any other shape.
View the video.
View the video of a leaf: the high surface area to volume ratio is
essential for exchange of gases between leaf tissue and the surrounding
Net (overall) movement of materials across membranes is also determined by
the total surface area (SA) of the cell in relation to its volume (V).
The smaller the cell, the larger its SA in relation to its V (SA/V), and
therefore the more efficient is the movement of particles.
The bigger the cell, the smaller the SA in relation to its V. The
effectiveness of diffusion places a limit on the size a cell can be.
An increase in the surface area will change the surface area to volume
ratio. View the video.
Which block size has the larger surface area to volume ratio: the large
or the small block?
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