JAMB - Biology (2021 - No. 33)
The sequence of the one-way gaseous exchange mechanism in a fish is?
mouth --> operculum -> gills
mouth -> gills > operculum
operculum > gills -> mouth
gills -> operculum --> mouth
Forklaring
Fish exchange gases by pulling oxygen-rich water through their mouths and pumping it over their gills. In some fishes, capillary blood flows in the opposite direction to the water, causing counter-current exchange. The gills push the oxygen-poor water out through openings in the sides(opercula) of the pharynx.