Surface area to volume ratio is vital in so many biological processes. When we’re talking about cells, which is most of the time, the important point is that the surface area to the volume ratio gets smaller as the cell gets larger.
Therefore cells are limited in their size because if the cell grows beyond a certain limit, not enough material will be able to cross the membrane fast enough to accommodate the increased cellular volume.
Here are some examples to help to remember how surface area to volume ratio plays its role:
If you were living in Africa you would rather have a large surface area to volume ratio as this would help you lose heat faster.
Alternatively, if you were living in the Antarctic you would want a small surface area to volume ratio.
This would reduce heat loss and conserve it in the body. Obviously it is cold at the Antarctic, so you would want to minimise heat loss.
Smaller animals tend to have larger surface area to volume ratios. For instance, a hamster has a larger surface area relative to its volume than an elephant!
Elephants have adapted to losing heat faster by having very large ears. This increases their surface area to volume ratio.
Heat is released from our bodies during respiration. This helps keep our organs warm, but it can be a problem if you cannot control your body temperature well.
In our bodies waste is carried by the circulatory system. The blood carries waste from cells around the body to the lungs, the skin, the liver and to the kidney.
But in single celled organisms they get rid of waste by it diffusing across their membranes. As they have a large surface area to volume ratio, diffusion of waste substances occurs rapidly.