SA:V ratio

What are the advantages of having a small size and a high SA:V ratio?

A high surface area to volume ratio will allow sufficient exchange to occur across the plasma membrane. Having a smaller size will decrease the requirements and needs of each cell and the rate of exchange will also increase.

What is diffusion?

Diffusion is the movement of particles from a higher solute concentration to a lower solute concentration (along the concentration gradient). The larger the concentration gradient the more rapid the rate of diffusion.

What can affect the rate of diffusion?

Increasing temperature can increase the rate of diffusion because the molecules move more rapidly. The permeability of the membrane will also affect the rate of diffusion The size of the solute is also another factors. If the molecule is too big it might not be able to pass through the membrane.

What does the amount of exchange in each organism depend on?

Large organisms have to exchange more material because their requirements are proportionally larger. The amount of exchange required is related to the volume of tissue rather than surface area.

What is equilibrium?

The concentration of the solute is the same through a solution of either side of the membrane or just balanced out through an area.

What happens to SA:V if an organism stays the same shape but becomes larger?

The volume increases more rapidly than the surface area. As organisms get larger (but stay the same shape) they have a smaller surface area available for exchange of materials.

What can be done to have enough SA for exchange of materials when the size increases?

To change the shape as size increases. Flattening the shape will result in a higher surface are to volume ratio because there will be more area available for exchange.

What is passive transport?

Transport that does not require energy.

Explain what is meant by SA:V ratio

Both surface area and volume increase as an object gets larger, but they do not increase by the same amount. Surface area is the area available for exchange and volume is the amount of functioning tissues.