Countercurrent exchange in the fish gill helps to maximise ________.
A) blood pressure
B) diffusion
C) active transport
D) osmosis

Question

Quizplus · Accepted Answer

Countercurrent exchange refers to the exchange of substances (such as oxygen and carbon dioxide) between two fluids flowing in opposite directions. In the fish gill, this mechanism helps to maximise diffusion of oxygen from the water into the blood, as well as the removal of carbon dioxide from the blood into the water. This is because the oxygen-rich water is always in contact with oxygen-poor blood, creating a concentration gradient that favours diffusion. Therefore, option B is the correct answer.

Countercurrent Exchange in the Fish Gill Helps to Maximise ________