SA:V ratio

What is compartmentalisation?

Organelles are surrounded by membranes to increase the surface area, allowing for more cellular functions. Together, the total area of a cell's internal membranes far exceeds that of its plasma membrane.

Body shape and heat loss

Organisms with a lower surface area to volume ratio will lose less body heat than those with a high surface to volume ratio. As a higher SA:V has more area for heat to be radiated off.

What is SA:V ratio?

Relationship between the cell's area of the plasma membrane and the volume of its cytoplasm

Why do some cells have higher SA:V ratio and how do they do so?

They need to absorb more nutrients than other cells. They can achieve this by flattening themselves into an oval shape, or by having extensions such as microvilli to increase their surface area. In that way there is a greater surface area for the nutrients to move into the cell.

Why are cells so small?

As the size of the cell increases, the SA:V ratio decreases. This means that the efficiency with which a cell obtains its nutrients (glucose, water oxygen) and removes its waste is reduced as its size increases. If the cell gets too large, it gets to a point where the process of diffusion cannot happen quick enough to service the increasing volume of the cell, causing the cell to die.