-Countercurrent flow in the respiratory systems of fish is a mechanism that accounts for
A) oxygen uptake by blood capillaries in the gills.
B) ventilation across fish gills.
C) the transport of blood from the gills to the fish's heart.
D) the transport of blood from the heart to the fish's main body mass.
E) the flow of blood in gills as opposed to the flow of blood in the main body mass of fish.

Question

-Countercurrent flow in the respiratory systems of fish is a mechanism that accounts for
A) oxygen uptake by blood capillaries in the gills. 
B) ventilation across fish gills. 
C) the transport of blood from the gills to the fish's heart. 
D) the transport of blood from the heart to the fish's main body mass. 
E) the flow of blood in gills as opposed to the flow of blood in the main body mass of fish.

Quizplus · Accepted Answer

Countercurrent flow in fish gills maximizes oxygen uptake by maintaining a gradient where water with higher oxygen content flows opposite to blood with lower oxygen content, enhancing diffusion into the blood capillaries.

-Countercurrent Flow in the Respiratory Systems of Fish Is a Mechanism