fish, insect gas exhange

Question 1

why cannot fish live on land

Answer 1

gills dry out
prevents o2 from diffusing into surface of gills
no longer supported by water the gills stick together

Question 2

countercurrent flow 3 marks

Answer 2

blood and water flow im oppposite directions
high oxygenated water comes in contact with low 02 blood.
diffuses
maintains a concentration gradient.