features of gas exchange surfaces

Question 1

what are the features of gas exchange surfaces in all animals

Answer 1

large SA
short diffusion pathway
moist and permeable to gases

Question 2

what are features of gas exchange surfaces that help to maintain a diffusion gradient?

Answer 2

circulation of blood
ventilation mechanisms

Question 3

what problems do specialised gas exchange surfaces in large multicellular organisms overcome?

Answer 3

overcome problems with having a low surface area to volume ratio

long diffusion distances

Question 4

usually gas exchange surfaces in large multicellular organisms have what>

Answer 4

large SA
short diffusion pathway
ventilation mechanisms to maintain conc gradient
permeability to gases
moist surfaces so O2 can dissolve in water and diffuse across them