[Campbell Biology P.995] According to the passage, why do mammals generally function less ef... | Practice Question

According to the passage, why do mammals generally function less effectively than birds at high altitudes in terms of oxygen acquisition?

  • A: Mammals have a higher metabolic rate requiring more oxygen.
  • B: Birds possess a more flexible diaphragm for increased ventilation.
  • C: Mammalian lungs do not completely empty with each breath, and inhalation mixes fresh air with residual air, leading to lower maximum PO2 in alveoli compared to birds' unidirectional flow.
  • D: Birds have a larger lung capacity relative to their body size, allowing for greater oxygen storage.

Explanation

Mammalian lungs do not completely empty with each breath, leading to mixing of fresh air with oxygen-depleted residual air, which results in a lower maximum PO2 in the alveoli. Birds, however, have a unidirectional flow of air through their lungs, allowing for more efficient oxygen uptake at high altitudes.