[Campbell Biology P.945] Small animals generally breathe more rapidly than large animals. Ba... | Practice Question

Small animals generally breathe more rapidly than large animals. Based on the principles discussed in the text regarding metabolic rate and body size, what is the primary biological reason for this observation?

  • A: Small animals have less efficient respiratory systems compared to large animals.
  • B: Small animals have a higher total metabolic rate, thus requiring more oxygen overall.
  • C: Small animals have a higher metabolic rate per unit of body mass (gram), leading to a greater demand for oxygen and faster removal of waste products, necessitating a higher breathing rate.
  • D: Large animals have proportionally larger lungs, allowing them to take in more oxygen per breath, thus requiring fewer breaths.

Explanation

The text states that 'Minimum metabolic rate per gram is inversely related to body size among similar animals.' This means that smaller animals have a significantly higher metabolic rate per unit of body mass than larger animals. To support this higher per-gram metabolism, small animals require a faster rate of oxygen delivery and waste removal, which is achieved through a higher breathing rate.