(a) Counter - current flow (system) ;
(b) This ensure efficient diffusion of oxygen from water into blood i.e there is continuous diffusion of oxygen from water
into blood ;
Eventually blood that leaves the gills has almost the same concentration of oxygen as the water that enter the gills /
maintains a steep diffusion gradient between water and blood ;
sharon kalunda answered the question on May 24, 2019 at 09:25
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