specialised transport systems- transport in animals

Question 1

Why do larger organism need specialise transport systems?

Answer 1

• metabolic demands are high= diffusion over long distances not enough to supply quantities needed
• small SA:V =amount of area to absorb substances becomes smaller
• molecules e.g hormones may be made in one place but needed in another
• waste products need to be removed from cells and transported to excretory systems

Question 2

mass transport system

Answer 2

-substances are transported in a mass of fluid with a mechanism for moving the fluid around the body

Question 3

open circulatory systems

Answer 3

• very few vessels to contain transport medium
• pumped straight from heart to body cavity of animal (haemocoel)
• in haemocoel transport medium is under low pressure
• comes into direct contact with cells and tissues where exchange takes place

Question 4

where are open circulatory systems mainly found

Answer 4

• invertebrate animals

- in insects, gas exchange takes place in tracheal system

Question 5

closed circulatory systems

Answer 5

-blood is enclosed in blood vessels and does not come into direct contact with cells in the body

Question 6

single closed circulatory systems

Answer 6

• found in fish
• the blood flows through the heart and is pumped out to travel all around body before returning
• blood passes through 2 sets of capilleries before it returns to heart
• in first, it exchanges oxygen and carbon dioxide
• in second, substances exchanged between blood and cells

Question 7

disadvantages of single closed circulatory systems

Answer 7

• as a result of passing through 2 blood vessels, blood is at v low pressure so returns to heart very slow= limits the efficiency of exchange processes
• however fish have a countercurrent exchange mechanism

Question 8

double closed circulatory systems

Answer 8

• blood is pumped from heart to lungs to pick up O2 and unload CO2 and then returns to heart
• blood flows through heart and is pumped out to travel all around the body before returning to heart
• each circuit passes tghrough 1 capillary network=high pressure and fast flow of blood maintained