Which statement best completes the sentence: Temperature, pulse and respiration rates tend to _________ as size of the animal _________.

Which statement best completes the sentence: Temperature, pulse and respiration rates tend to _________ as size of the animal _________.

• A. A shallow, decreases
• B. B increase, decreases
• C. C decreases slowly, decreases rapidly
• D. D decreases, decreases

Answer: (B)

Smaller animals have higher metabolic rates per unit body mass, so their tissues demand more oxygen and need to eliminate more carbon dioxide in a given time. To meet that demand, the heart beats faster and breathing rate increases. Metabolic heat production is also greater per gram in small animals, so body temperature relates to this higher activity level, contributing to warmer or more actively regulated temperatures in smaller species. Because all three vital signs rise with the need to support this higher metabolism, as size decreases those rates tend to increase. The statement that temperature, pulse and respiration rates increase as the animal gets smaller best fits this pattern.

Smaller animals have higher metabolic rates per unit body mass, so their tissues demand more oxygen and need to eliminate more carbon dioxide in a given time. To meet that demand, the heart beats faster and breathing rate increases. Metabolic heat production is also greater per gram in small animals, so body temperature relates to this higher activity level, contributing to warmer or more actively regulated temperatures in smaller species. Because all three vital signs rise with the need to support this higher metabolism, as size decreases those rates tend to increase. The statement that temperature, pulse and respiration rates increase as the animal gets smaller best fits this pattern.