7.1 Specialised Exchange Surfaces

Question 1

Why is diffusion alone enough to supply the needs of single called organisms?

Answer 1

The metabolic activity is low, so oxygen demands and carbon dioxide production of the cell are relatively low
SA:V ratio of the organism is large

Question 2

What are exchange surfaces?

Answer 2

Surfaces over which materials are exchanged from one area to another

Question 3

Features of effective exchange surfaces

Answer 3

Increased surface area
Thin layers
Good blood supply
Ventilation to maintain concentration gradient

Question 4

How does increased surface area make a more effective exchange surface?

Answer 4

Provides the area needed for exchange

Overcomes limitations of SA:V ratio of larger organisms

Question 5

How do thin layers provide a more effective exchange surface?

Answer 5

Distances that substances have to diffuse are short, so the process is fast and efficient

Question 6

Why is good blood supply important for an exchange surface?

Answer 6

The steeper the concentration gradient, the faster the diffusion
Substances are constantly delivered and removed from the exchange surface
Maintains a concentration gradient for diffusion

Question 7

Why should there be ventilation to maintain a diffusion gradient?

Answer 7

A ventilation system helps maintain concentration gradients and make the process more efficient