The bar-headed goose (*Anser indicus*) is famous for its high-altitude migration over the Himalayas. Unlike most birds that fly at lower altitudes where oxygen is abundant, these geese routinely fly at altitudes exceeding 8,000 meters. To sustain flight in such hypoxic environments, the bar-headed goose possesses hemoglobin with an exceptionally high affinity for oxygen, allowing it to load oxygen at its lungs even under low pressure. Additionally, their capillaries are spaced closer together in their flight muscles compared to other geese, which decreases the diffusion distance for oxygen from the blood to the muscle cells. However, this adaptation does not significantly increase their overall aerobic capacity under sea-level conditions.
According to the text, which statement is true about the physiological adaptations of the bar-headed goose?
- The close spacing of capillaries in their flight muscles reduces the distance that oxygen must diffuse from the blood to muscle cells.Cevap
- BTheir physical adaptations provide them with a significantly higher aerobic capacity at sea level than other goose species.
- CThey migrate at altitudes exceeding 8,000 meters because they are physiologically unable to sustain flight at lower altitudes.
- DMost other bird species fly at lower altitudes where oxygen is relatively abundant.