exchange surface and transport SLOP

Question 1

State the three main factors that affect the need for an exchange system

Answer 1

Size, SA:Vol ratio and level of activity

Question 2

Explain why smaller organisms have a lower demand for oxygen than larger organisms

Answer 2

Smaller organisms have a larger SA:V ratio than larger organisms; simple diffusion can be sufficient for unicellular organisms but due to many-layered multicellular organisms, it would be too slow. Multicellular organisms therefore need transport system