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
The correct answer is: B
Explanation
Fish exchange gases by pulling oxygen-rich water through their mouths and pumping it over their gills. In some fish, 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.
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