Question

Which of the following statements about bird respiration is FALSE?

A. Air flowing through the air channels in the lungs moves in a tidal fashion.
B. It takes two ventilation cycles for a single breath of air to move through a bird's respiratory system.
C. The unidirectional flow of air through a bird's lungs maintains a larger concentration gradient for diffusion than can be obtained through tidal breathing.
D. Bird lungs receive fresh air during both inhalation and exhalation.
E. Oxygen is exchanged between the air and the bloodstream in the lungs, but not in the air sacs.

Answer 1

The false statement about bird respiration is that air flows in a tidal fashion within bird lungs, when in fact it flows unidirectionally. So the correct option is A.

Step-by-step explanation:

The student asked which statement about bird respiration is FALSE. The correct answer is A: "Air flowing through the air channels in the lungs moves in a tidal fashion." This statement is false because bird respiration is characterized by a unidirectional airflow, not a tidal (back-and-forth) flow as it is in mammals. In bird respiration, fresh air is received during both inhalation and exhalation, and gas exchange happens in the lungs where the air is unidirectionally moved into the posterior air sacs, then to the lungs, and finally to the anterior air sacs before being expelled. The bird's respiratory process is highly efficient, maintaining a larger concentration gradient for diffusion, which is further enhanced by the counter-current exchange system.

Answer 2

Answer:D

Explanation: The pulmonary air sacs of birds only permit a unidirectional flow of air through the lungs. Unidirectional flow means that air is inhale and exhale through one trachea alternatively. This means the bird lungs only receive largely fresh air which has a high oxygen content during inhalation and do not receive fresh during exhalation. While air flow bidirectional in mammals.