Question

Which one of the following statements is incorrect :

• A. In insects, circulating body fluids serve to distribute oxygen to tissues
• B. The principle of countercurrent flow facilitates efficient respiration in gills of fishes
• C. The residual air in lungs slightly decreases the efficiency of respiration in mammals
• D. The presence of non-respiratory air sacs increases the efficiency of respiration in birds

Answer 1

The correct option is C The residual air in lungs slightly decreases the efficiency of respiration in mammals

The residual air is the air that remains in the lungs after the most forceful expiration. The residual air remains in the lungs. Hence, it has no effect on respiration efficiency in mammals. The presence of non-respiratory air sacs increases the efficiency of respiration in birds. These air sacs increase the metabolic rate in birds. In insects, circulating body fluids serve to distribute oxygen to tissues. Countercurrent oxygen flow is the flow of blood through the gills in the opposite direction as the water flowing over the gills. This facilitates efficient respiration in gills of fishes.

Thus, the correct answer is C

('The residual air in the lungs slightly decreases the efficiency of respiration in mammals.')