Question

The countercurrent exchange mechanism in fish gills

a. Maximizes oxygen diffusion into the bloodstream.

b. Is a less efficient mechanism for gas exchange than that used in mammalian lungs.

c. Occurs because the flow of blood is in the same direction as water flowing across the gills.

d. Facilitates diffusion of carbon dioxide into the blood of the fish.

e. Facilitates diffusion of oxygen to the environment.

Answer 1

a. Maximizes oxygen diffusion into the bloodstream.

because The countercurrent exchange mechanism in fish gills maximizes oxygen diffusion into the bloodstream.