SA: V ratio Flashcards
What is the SA:V ratio?
What is the relationship between the SA:V ratio and the rate of diffusion?
As the ratio increases the rate of diffusion increases because the surface area available for diffusion increases and the distance of diffusion decreases.
What is the relationship between the SA:V ratio and the size of an animal?
The larger an animal gets the lower their surface area to Volume ratio gets. This is because larger organisms have a much larger volume compared to their surface area.
Why do multicellular organisms with a small SA:V ratio need exchange and transport systems?
They have a very low surface area to Volume ratio, meaning that the surface area available for the exchange of substances is relatively small, and there is a large distance between the outside of the organism and the middle of it. This means they need to have exchange surfaces with special adaptations to make the exchange of substances more efficient and sufficient enough to meet their high metabolic rate.
Why do unicellular organisms like amoeba not need specialised exchange surfaces for gas exchange?
They have a very large surface area to Volume ratio, meaning there is a big surface area for the exchange of surfaces, and also, there is a smaller distance from the outside of the organism to the middle of it. As a result, it can simply exchange substances across its surface through simple diffusion.
What is the relationship between the SA:V ratio and the metabolic rate?
Smaller animals with a high SA:V ratio usually have a higher metabolic rate per unit of body mass as their large surface area means they lose heat quickly and they need to expand more energy to raise their body temperature.
What is the link between the body shape and SA:V ratio?
Certain changes to the body shape such as large ears which increase the surface are of the organism also increase thw surface area to Volume ratio.
