Reptiles are ______ blooded.

Reptiles are ______ blooded.

• A. Cold-blooded
• B. Warm-blooded
• C. Cold blooded
• D. Warm blooded

Answer: (A)

Reptiles are ectothermic, meaning their body temperature largely tracks the surrounding environment. They depend on external heat sources—sunlight for warming and shade for cooling—and regulate temperature mainly through behavior rather than metabolic heat production. This is why they’re described as cold-blooded. The hyphenated form cold-blooded is the standard way to express this idea. In contrast, warm-blooded (endothermic) animals maintain a relatively constant internal temperature through metabolism. So the best completion is cold-blooded.

Reptiles are ectothermic, meaning their body temperature largely tracks the surrounding environment. They depend on external heat sources—sunlight for warming and shade for cooling—and regulate temperature mainly through behavior rather than metabolic heat production. This is why they’re described as cold-blooded. The hyphenated form cold-blooded is the standard way to express this idea. In contrast, warm-blooded (endothermic) animals maintain a relatively constant internal temperature through metabolism. So the best completion is cold-blooded.