surface area to volume ratio

• the relationship between the size of the organism/structure & its SA:V ratio plays a significant role in the types of adaptations it will have
• when working out SA:V ratio, divide the surface area by the volume
• smaller organisms have larger SA:V ratios, so are able to efficiently diffuse substances across their surface, as there is also a smaller distance from the outside of the organisms to the middle of it
• larger organisms have smaller SA:V ratios, so can't diffuse gases across their surface as there is also a larger distance from the middle to the outside, so need adaptations to help increase surface area
• larger organisms will typically have a higher metabolic rate, which demands efficient transport of waste out of cells & reactants into cells