transport in animals

Question 1

why do multicellular animals need transport systems?

Answer 1

• they have a high metabolic rate; multicellular animals need lots of oxygen + food and produce lots of waste so diffusion over long distances is not enough to supply the quantities needed
• they have a small sa:v ratio; larger diffusion distances and small SA to absorb/remove substances

Question 2

features of a closed circulatory system

Answer 2

blood enclosed in blood vessels and doesn’t have direct contact with all cells
heart pumps blood under pressure, blood returns to the heart
substances enter/leave blood through blood vessel walls
blood flow of tissues adjusted by widening/constricting blood vessels
an effective transport system for multicellular animals as it allows blood to travel rapidly under high pressure to wherever it’s needed