The main phenomenon that increases the efficiency of gas exchange in fish gills is the
A)countercurrent exchange mechanism.
B)co-current exchange mechanism.
C)high degree of oxygen saturation of water.
D)back-and-forth movement of water that maximizes oxygen uptake.
E)very high blood pressure found in the circulatory system of fishes.

Question

Quizplus · Accepted Answer

The countercurrent exchange mechanism in fish gills allows for a gradient to be maintained between the oxygen-rich water and oxygen-poor blood, thus maximizing oxygen uptake in the blood. This mechanism leads to a significantly higher efficiency of gas exchange compared to a co-current exchange mechanism. The degree of oxygen saturation of water and the back-and-forth movement of water are important factors as well, but they do not increase the efficiency of gas exchange as much as the countercurrent exchange mechanism. The blood pressure in fish circulatory systems is not very high, so it is not a major factor in the efficiency of gas exchange in fish gills.

The Main Phenomenon That Increases the Efficiency of Gas Exchange