What are the uses of exchange systems?

How does the surface area: volume ratio of a smaller organism compare to that of a larger organism?

What is the equation for the surface area and volume of a sphere?

What is the equation for the surface area and volume of a cylinder?

How does exchange occur in single-celled organisms?

Why do multicellular organisms need specialised exchange surfaces?

What are the features of exchange surfacs?

Give an example of an exchange surface with large surface area

Give an example of an exchange surface which is thin (short distance)

Give an example of an exchange surface which has a good blood supply and/or ventilation