Which term describes an organism that is internally warmed by a heat-generating metabolic process?

• A. An organism whose body does not produce much internal heat
• B. A cold-blooded animal
• C. An organism that relies on environmental heat
• D. An organism that is internally warmed by a heat-generating metabolic process

Answer: (D)

Endothermy is the ability of an organism to generate heat internally through metabolic activity and to maintain a relatively constant body temperature. This describes an organism that is warmed from within by its own heat production, which is exactly what the statement is conveying. Mammals and birds are classic examples, able to stay active in a variety of environments because they produce heat metabolically and often have insulation. In contrast, organisms that rely on environmental heat or are described as cold-blooded produce little internal heat and largely depend on the surroundings to determine their body temperature, so they don’t fit this description.