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  3. Animals live longer when their calorie intake is restricted to two-thirds of wha

Animals live longer when their calorie intake is restricted to two-thirds of wha

游客2025-02-20  44
问题 Animals live longer when their calorie intake is restricted to two-thirds of what is considered normal for their species. Animals so restricted are also generally healthier: most disease, including cancer, diabetes, and neurodegenerative illness, are forestalled. Q2This phenomenon was long attributed to a simple slowing of metabolism (cells’ production of energy from fuel molecules) and consequent reproduction of its toxic by-products in response to less food. In fact, however, calorie restriction does not slow mammalian metabolism, and Q1in yeast and worms, metabolism is both sped up and altered. Some scientists now theorize that calorie restriction is a biological stressor that, like natural food scarcity, induces a more complex defensive response, which in mammals includes changes in cellular defenses and repair. [br] The passage implies which of the following about the explanation mentioned in the highlighted text?
选项 A、There are empirical findings that conflict with a presumption of the explanation.
B、The explanation predicts that the effect of calorie restriction on longevity will be the greatest for the species with the highest rate of metabolism.
C、The explanation predicts that the effects of calorie restriction will be uniformly positive.
答案 A
解析 A．There are empirical findings that conflict with a presumption of the explanation．有一些实验上的发现与这一解释的前提假设相矛盾。
解析：高亮部分提到的解释指的是新陈代谢降低导致动物更健康。其前提假设是卡路里摄入量的减少会降低新陈代谢。而第四句中的哺乳动物、酵母和蠕虫卡路里摄入量减少后，新陈代谢并没有降低，因此与之前观点的前提假设构成矛盾。A正确。
B．The explanation predicts that the effect of calorie restriction on longevity will be the greatest for the species with the highest rate of metabolism．这种解释预测到对于新陈代谢率最高的物种来说，卡路里限制对于寿命的影响是最大的。
解析：本文只提到卡路里限制导致新陈代谢的降低进而提升动物寿命，但是并没有指出新陈代谢降低的程度和寿命提升程度之间的比例关系，因此该选项未必正确，不选。
C．The explanation predicts that the effects of calorie restriction will be uniformly positive．这种解释预测到卡路里限制所产生的影响是完全积极的。
解析： “完全积极”这种说法太极端，文中看不出来。不选。
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