Transport of substances

Question 1

What happens as size of organisms increases

Answer 1

The surface Area to Volume ratio decreases.
Diffusion distance increases
Metabolic rate increases
Diffusion becomes insufficient and a mass transport system is needed

Question 2

Features of a mass transport system

Answer 2

1. A network to move through (eg. vessels)
2. A medium for movement ( a fluid eg. blood)
3. Controlled direction - to move substances to/from where they are needed ( a pressure gradient is created by the heart and valves control direction)
4. Maintenance of speed - (eg. contraction of heart and elastic recoil of arteries helps to maintain the pressure gradient , thus speed )