Exchange Surfaces and breathing

Question 1

Why is diffusion enough to supply the needs of single-celled organisms

Answer 1

-Metabolic activity is usually low, oxygen demands are low and production of carbon dioxide is low
-SA:V ratio is large

Question 2

Features of specialised exchange surfaces

Answer 2

-Increased surface area
-Thin layers
-Good ventilation to maintain diffusion gradient
-Good blood supply (substances are constantly delivered to and removed)

Question 3

Nasal Cavity

Answer 3

-Large surface area, good blood supply which warms air to body temperature
-Hairy lining, secretes mucus to trap dust and bacteria, protect lungs from irritation and infection
-Moist surfaces, increase humidity of incoming air, reduce evaporation from the exchange surfaces