4.2 - Gas Exchange

Question 1

Explain SA:V ratio concept

Answer 1

• as the organism gets bigger, the SA:V ratio gets smaller

Question 2

Why are transport systems needed?

Answer 2

• required to take material between cells and exchange surface

Question 3

Whether the transport system is specialised or not depends on what?

Answer 3

1. the SA:V ratio
2. how active the organism is

Question 4

Why do larger organisms need mass transport systems and specialised gas exchange surfaces?

Answer 4

• larger animals have a smaller SA: V ratio so it is difficult to exchange enough substances to supply a larger volume of animals through a relatively small surface area
• larger organisms have a higher metabolic rate so they quire O2 and other nutrients at a faster rate