Transport Systems in Multicellular Animals

Question 1

Why do multicellular animals need transport systems? (5)

Answer 1

• High metabolic demands that require lots of oxygen and food
• Small SA:V
• Transporting molecules from the site they’re created to the site they’re needed
• Transport of digested food
• Removal of waste products

Question 2

What are the features of a circulatory system? (3)

Answer 2

• Have a liquid medium that circulates around the system
• Have vessels that carry the transport medium
• Have a pumping mechanism to move the fluid around the system

Question 3

What is meant by an open circulatory system? What are some features? (4)

Answer 3

• Very few vessels that contain the transport medium
• Transport medium is pumped from heart into body cavity of the animal (called the haemocoel)
• Low pressure
• Fluid comes in direct contact with the cells

Question 4

What is an insects circulatory system like? (5)

Answer 4

• Open circulatory system
• Insect blood is called haemolymph
• Doesn’t carry oxygen and carbon dioxide, only nitrogenous waste and cells defence against disease
• Steep conc. gradients can’t be maintained
• Amount of haemolymph cannot be varies to meet changing demands for particular tissues`

Question 5

What is meant by a closed circulatory system? (5)

Answer 5

• All blood is enclosed within vessels
• Blood doesn’t come in direct contact with cells
• Blood directly returns to heart
• Substances enter and leave through diffusion through the vessels
• Amount of blood flowing to certain tissues can be controlled by widening or narrowing blood vessels

Question 6

What is meant by a single closed circulatory system?

Answer 6

Blood travels only once through the heart for each complete circulation of the body
e.g. fish

Question 7

What is meant by a double closed circulatory system?

Answer 7

Blood travels twice through the heart for each circuit of the body

Question 8

Why do some animals need a double circulatory system? (2)

Answer 8

• Very active (need more oxygen)

- Regulate their own body temperature

Question 9

How is blood pumped in a double circulatory system? (2)

Answer 9

• Blood is pumped from the heart to the lungs to pick up oxygen and unload carbon dioxide then returns to the heart
• Blood is then pumped to the rest of the body before returning to the heart again