3.3.2 gas exchange

Question 1

how does gas exchange occur in single-celled organisms?

Answer 1

absorb and release gases by diffusion through cell surface membranes
they have a large surface area, a thin surface and a short diffusion pathway
no need for a specialised gas exchange system

Question 2

how is the gas exchange system of an insect adapted?

Answer 2

tracheae which branch off into tracheoles which have thin permeable walls
oxygen diffuses directly into respiring cells