JAMB - Biology (2016 - No. 32)

The sequence of the one-way gaseous exchange mechanism in a fish is

gills ⇢ operculum ⇢ mouth

mouth ⇢ gills ⇢ operculum

mouth ⇢ operculum ⇢ gills

operculum ⇢ mouth ⇢ gills