Question

Describe how the countercurrent mechanism of gas exchange works. You are welcome to include pictures of your own labeled drawings in your answer but not pictures from other sources. Lastly, briefly answer this question: What would happen if water moved backwards through the gills?

Answer 1

First I have attached countercurrent exchange system for gas .

If water from the gills flow in backward direction than it will make co current system. And with co current system it is not possible to trap 100% dissolved oxygen.

Normal water moves through mouth and than to gill this forms a counter current system which teap maximum dissolved oxygen. But if water moves backwards means enter through gills and then exit through mouth than it will form a co current system where both fluid will move in a same direction and this will limit exchange of gas up to a certain point maximum 50%