Test 03-Passage 3:HOW DOES THE BIOLOGICAL CLOCK TICK? 纠错
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AOur life span is restricted. Everyone accepted this as "biological" obvious. `Nothing lives forever!` However, in this statement we think of artificially produced, technical objects, products which are subjected to natural wear and tear during use. This leads to the result that at some time or other the object stops working and is unusable (`death` in the biological sense). But are the wear and tear and loss of function of technical objects and the death of living organism really similar or comparable?

A 我们的寿命是有限的。每个人都已经接受了这一点,因为从“生物学”角度来讲这是显而易见的。“没有什么会永生!”然而,在这句话中,我们想到了那些人造的技术产品,这些产品在使用过程中会产生自然磨损。这就意味着它们终究会有一天停止工作、不能用了(生物学意义上的“死亡”)。但这些技术产品的磨损及功能丧失与生物体的死亡这两者之间真的具有相似性或可比性吗?

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BOur `dead` products are `static`, closed systems. It is always the basic materials which constitutes the object and which, in the natural course of things, is worn down and becomes `older`. Ageing in this case must occur according to the laws of physical chemistry and of thermodynamics. Although the same law holds for a living organism, the result of this law is not inexorable in the same way. At least as long as the biological system has the ability to renew itself it could actually become older without aging; an organism is an open, dynamic system through which new materials continuously flows. Destruction of old material and formation of new material are thus in permanent dynamic equilibrium. The material of which the organism is formed changes continuously. Thus our bodies continuously exchange old substance for new, just like the spring which more or less maintains its form and movement, but in which the water molecules are always different.

B 我们所谓“死掉”的产品是指一些“静态的”、封闭的系统。构成物体的基本材料总是会在自然过程中逐渐磨损,变得“老化”。根据物理化学和热力学的规律,在这种情况下老化是必然的。虽然相同的规律也适用于生物体,但这一规律并不会以同样的方式产生不可抗拒的结果。至少只要一个生物系统有能力自我更新,它就确实能够不断成长但不会老化;生物体是一个开放、动态的系统,新物质会通过这个系统不断流动。因此旧物质的消逝和新物质的形成总是处于永久的动态平衡中。形成生物体的物质不断改变,于是我们体内的旧物质也持续不断地被新物质替换,就像喷泉,它能大体上保持自身的形态和运动状态,但是其中的水分子总是不同的。

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CThus aging and death should not be seen inevitable, particularly as the organism possesses many mechanisms for repair. It is not, in principle, necessary for a biological system to age and die. Nevertheless, a restricted life span, ageing and death are the characteristics of life. The reason for this is easy to recognise: in nature, the organisms either adapt or are regularly replaced by new types. Because of the changes of genetic material (mutations) these have new characteristics and in the course of their individual lives they are tested for optimal or better adaption to the environmental conditions. Immortality would disturb this system – it needs room for new and better life. This is the basic problem of evolution.

C 因此,老化和死亡不该被看作是不可避免的,尤其当生物体拥有许多修复机制时。从理论上讲,一个生物体的老化和死亡不是必然的。尽管如此,有限的寿命、衰老、然后死亡构成了生命的基本特征。原因则显而易见:本质上,现存的生物体要么适应环境,要么有规律地被新的物种代替。因为基因物质的变化(突变),生物体拥有了新的特征,并且个体生命的过程也在考验它们对周围的环境条件是否有最佳的或更好的适应性。永生可能会打乱这个系统,因为它需要为新的、更好的生命提供空间。这就是进化的本质问题。

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DEvery organism has a life span which is highly characteristic. There are striking differences life span between different species, but within one species the parameter is relatively constant. For example, the average duration of human life has hardly changed in thousands of years. Although more and more people attain an advanced age as a result of the developments in better medical care and better nutrition, the characteristic upper limit for most remains 80 years. A further argument against the simple wear and tear theory is the observation that the time within which organism age lies between a few days (even a few hours for unicellular organisms) and several thousand years, with mammoth trees.

D 每个生物体都有极具特色的寿命。不同的物种其寿命也有着显著差别,但在同一物种中,这个参数相对恒定。例如,几千年来人类的平均寿命几乎没变。虽然由于医疗服务的发展和营养的改善,越来越多的人达到高龄,但对大多数人来说人类普遍的寿命上限仍是80岁。此外,对抗简单磨损理论的另一个论点认为,生物体老去的时间短则几天(对单细胞生物来说甚至是几小时),长则几千年,比如巨杉。

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EIf a life span is genetically determined biological characteristic, it is logically necessary to propose the existence of an internal clock, which in some way measures and controls the ageing process and which finally determines the death as the last step in a fixed programme. Like the life span, the metabolic rate has for different organisms a fixed mathematical relationship to the body mass. In comparison to the life span this relationship is `inverted`: the larger the organism, the lower its metabolic rate. Again this relationship is valid not only for birds, but also, similarly on average within the systematic unit, for all other organisms (plants, animals, unicellular organisms).

E 如果寿命是一个由基因决定的生物特征,那么按照逻辑我们就有必要提出这样一个观点:生物体内存在一个内部时钟,这个时钟以某种方式测量和控制着衰老的进程,并且最终决定这一固定程序的最后一步:死亡。就像寿命,对于不同的生物体,其代谢速率跟体重有一个固定的数据关系。同寿命相比,这个关系是“反向的”:生物体体重越大,其代谢速率越低。另外,这个关系不仅适用于鸟类,由于系统单元内的情况大体类似,因此也适用于其他所有生物体(植物、动物、单细胞生物)。

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FAnimals which behave `frugally` with energy become particularly old, for example, crocodiles and tortoises. Parrots and birds of prey are often held chained up. Thus they are not able to `experience life` and so they attain a high life span in captivity. Animals which save energy by hibernation or lethargy (e.g. bats or hedgehogs) live much longer than those which are always active. The metabolic rate of mice can be reduced by a very low consumption of food (hunger diet). They can live twice as long as their well-fed comrades. Women become distinctly (about 10 percent) older than men. If you exam the metabolic rate of the two sexes you establish that the higher male metabolic rate roughly accounts for the lower male life span. That means that they live life `energetically` – more intensively, but not for as long.

F 那些在能量消耗方面比较“节约”的动物寿命尤其长,例如鳄鱼和乌龟。鹦鹉和猛禽经常被锁链栓着,因此往往不能“体验生活”,于是在圈养状态下获得了较长的寿命。有些能通过冬眠或嗜睡来保存能量的动物(例如蝙蝠或刺猬)通常比那些总是很活跃的动物活得更长久。老鼠的代谢速率可以通过减少食物消耗量(饥饿饮食法)来降低,他们的寿命可能比那些平日吃饱喝足的同类寿命长一倍。另外,女性的寿命很明显比男性的寿命长(大约10%)。如果研究两性的代谢速率,你会发现男性代谢速率较高,这就意味着男性的寿命较短,也就是说他们在生活中比较耗费能量——比女性活动更为剧烈,但生命持续的时间没有女性长。

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GIt follows from the above that sparing use of energy reserves should tend to extend life. Extreme high performance sports may lead to optimal cardiovascular performance, but they quite certainly do not prolong life. Relaxation lowers the metabolic rate, as does adequate sleep and in general an equable and balanced personality. Each of us can develop his or her own `energy saving programme` with a little self-observation, critical self-control and, above all, logical consistency. Experience will show that to live in this way not only increases the life span but is also very healthy. This final aspect should not be forgotten.

G 从上面的讨论可以看出,节约使用我们的能量储备应该可以延长寿命。极端的剧烈运动可能会让心血管功能达到最佳状态,但肯定不会延长寿命。放松下来可以降低代谢率,而充足的睡眠及大体平和的性格也会起到相同的作用。只要进行一些自我观察、严格的自我控制.尤其重要的是保持逻辑连贯性,我们每个人都能发展自己的“节能程序”。经验表明这样的生活方式不仅能够延年益寿,而且非常健康。最后这点绝对不要忘记。

Complete the notes below.

Choose NO MORE THAN TWO WORDS from the passage for each answer.

Write your answers in boxes 33-36 on your answer sheet.

•Objects age in accordance with principles of and of

•Through mutations, organisms can better to the environment

would pose a serious problem for the theory of evolution
显示答案
正确答案: 33. physical chemistry 34. thermodynamics 35. adapt 36. immortality

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