Why is the respiratory system of a bird more efficient than the human respiratory system?

Question

a The bird respiratory system does not mix exhaled air with inhaled air.

b A bird lung contains multiple alveoli, which increases the amount of surface area available for gas exchange.

c The human respiratory system ends in small parabronchi, which reduce the amount of surface area available for gas exchange.

d A bird lung contains multiple alveoli, which increases the amount of surface area available for gas exchange, and the human respiratory system ends in small parabronchi, which reduce the amount of surface area available for gas exchange.

e The bird respiratory system does not mix exhaled air with inhaled air, a bird lung contains multiple alveoli, which increases the amount of surface area available for gas exchange, and the human respiratory system ends in small parabronchi, which reduce the amount of surface area available for gas exchange.

Answer 1

The bird has to exert more energy in flight, therefore they need a cleaner form of air and they need to breathe fast enough to fly. Evolution made the bird have a superior respiratory system, we have superior brains.

Answer 2

e

Answer 3

a

Answer 4

b