Question

Which of the following statements is incorrect?

• A. The principle of countercurrent flow facilitates efficient respiration in gills of fishes.
• B. Amoeba gets oxygen through simple diffusion across their cell membrane from the surrounding water.
• C. The residual air in lungs slightly decreases the efficiency of respiration in mammals.
• D. Whales and dolphins do not have lungs.

Answer 1

The correct option is D

Whales and dolphins do not have lungs.

Whales and dolphins, like all other mammals, have lungs. Unlike fish these marine mammals are not equipped with gills, which fish and other aquatic animals use to extract oxygen from water; instead, whales and dolphins need to rise to the surface of the water to inhale and exhale oxygen through their blow holes (structures present instead of a nose). These blow holes are surrounded by muscles that keep the hole closed when the whale or dolphin is under water and open it when the animal is at the surface and needs to breathe.