2019年10月26日托福阅读真题+题目+答案：Dinosaurs: Warm-blooded or Cold-blooded?

2019年10月26日托福阅读真题+题目+答案：Dinosaurs: Warm-blooded or Cold-blooded?

Some animals are said to be warm-blooded while others are considered cold-blooded, but these terms are somewhat misleading since they seem to imply something about the actual temperature of an animal's blood or body. In fact, many cold-blooded animals employ various devices to keep their internal body temperatures quite high, whereas many warm-blooded animals sometimes have quite low body temperatures--during winter hibernations, for instance. The real issue is whether body temperature is regulated metabolically or in some other way. Metabolism refers to those internal chemical processes, such as digestion, necessary for maintaining life. A high rate of basal metabolism, which we typically find in birds and mammals, produces considerable internal heat. Endothermy is the pattern of thermoregulation whereby core body temperature depends on the high and internally controlled generation of heat by metabolic processes. Ectothermy is the pattern of thermoregulation whereby body temperature depends upon the uptake of heat from the environment. Reptiles are typical ectotherms, which is why those who keep reptiles must often use heating pads to keep their pets warm.

For over thirty years paleontologist Robert T. Bakker has argued that dinosaurs were endotherms, like mammals or birds and unlike lizards or alligators. Why is this categorization important? It is because endotherms are typically capable of much more prolonged periods of high activity. Lizards and alligators can move very fast when necessary, but they are active in spurts. A snake's strike or a crocodile's lunge can be faster than the eye can see, but such ectothermic hunters cannot pursue prey for mile after mile, as do endothermic wolves or cape dogs.

In the early 1970s, Bakker developed an argument for endothermy as the best explanation of the fact that dinosaurs were the culmination of an evolutionary trend toward ever more upright postures. Like present-day lizards, the original reptiles were sprawlers, meaning their legs were placed on the side of the body rather than directly underneath it. Dinosaurs evolved from a kind of reptile called a thecodont. Thecodonts were not sprawlers; they had achieved a semierect stance. The earliest dinosaurs had made the transition to a fully。。。。。。余下托福阅读原文省略！

1.The word "employ" in the passage is closest in meaning to

A. need

B. use

C. develop

D. possess

2. What can be inferred from paragraph 1 about ectotherms?

A. They are not often kept as pets.

B. They typically have low metabolic rates.

C. They generate their own internal heat.

D. They maintain a more consistent body temperature than do endotherms.

3. According to paragraph 2, Bakker's argument suggests that dinosaurs

A. tended to move in quick spurts

B. could not be categorized as either endotherms or ectotherms

C. moved in ways similar to lizards and alligators

D. could be active for long periods of time

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