Which term defines an animal whose body temperature is regulated by the environment?

Which term defines an animal whose body temperature is regulated by the environment?

• A. Vertebrate
• B. Reptile
• C. Scales
• D. Cold-blooded

Answer: (D)

Animals that regulate their body temperature using the surrounding environment are ectotherms, commonly described as cold-blooded. This term directly captures the idea that their internal temperature follows the ambient temperature, so their heat comes largely from outside sources. Among the options, cold-blooded fits best because it names this heat-regulation strategy. Vertebrate is too broad and just means having a backbone, not how temperature is controlled. Reptile is a group that includes many such animals, but it isn’t a general descriptor of temperature regulation. Scales describe skin, not temperature control. Endotherms would be warm-blooded, regulating heat internally.

Animals that regulate their body temperature using the surrounding environment are ectotherms, commonly described as cold-blooded. This term directly captures the idea that their internal temperature follows the ambient temperature, so their heat comes largely from outside sources. Among the options, cold-blooded fits best because it names this heat-regulation strategy. Vertebrate is too broad and just means having a backbone, not how temperature is controlled. Reptile is a group that includes many such animals, but it isn’t a general descriptor of temperature regulation. Scales describe skin, not temperature control. Endotherms would be warm-blooded, regulating heat internally.