Livingthingscanregulatetheirownactivitiesinsuchawaythattheyfitintotherhythms(节奏)innature.Forexampleplantsconsume(大量吸收)sunshineduringthedayanddomostoftheirbreathingatnight.Smallanim

Question

Living things can regulate their own activities in such a way that they fit into the rhythms ( 节奏 ) in nature. For example plants consume ( 大量吸收 ) sunshine during the day and do most of their breathing at night. Small animals which live in very hot regions remain deep in their holes during the heat of the day and only come out at night to obtain food. These rhythmic patterns of activity in living things can be called biological clocks.

Scientists have discovered some very interesting facts about biological clocks. Their most important discovery is that although   biological clocks approximately ( 近似地 ) correspond to the rhythms of day and night light and darkness they do not always depend on them. Many biological clocks are independent. How can this be proved? It can be proved by showing that a biological clock will continue to operate even when its surroundings are changed so that it can no longer respond to alternating periods of lights and darkness.

We will take the crab ( 蟹 ) as an example. This animal is a living clock. It indicates ( 指出 ) the time by the color of its skin which is dark during the day and lighter in color during the night. The daytime darkness of the crab's skin which prevents its enemies from noticing it and also prevents the crab from getting too hot is repeated every 24 hours. The alternating colors of the skin appear to follow the alternating rhythm of day and night. How can we prove the statement that crab is an independent clock which creates its own rhythm its own time? Perhaps it only responds to sunlight by growing darker when in contact with sunshine and growing lighter in color when the sun sinks behind the horizon ( 地平线 )?

To answer this question biologists did a simple experiment. They kept the crab in a dark room at a constant temperature for two months. They found that the skin of the crab continued to change color according to the same 24-hour rhythm following the movements of the sun outside. In this way they proved that the crab's biological clock was independent of events in its natural surroundings. It was not just a series of responses to external events.

　　 1. Biological clocks in living things are——.

　　　　  A. natural rhythms

　　　　  B. the alterations of day and night

　　　　  C. living thing's activities corresponding to some natural rhythms

　　　　  D. the repetition of activities of living things

　　 2. The author compares a crab to——.

　　　　  A. a biological clock 　　　　　　　　   B. an example of biological clock

　　　　  C. a living clock 　　　　　　   　　　　  D. a model of biological clocks

　　 3. A crab is an example of biological clocks in living things because it

　　　　  A. looks like clocks

　　　　  B. has dark skin

　　　　  C. creates its own time

　　　　  D. alternates color of its skin to follow the alternating rhythm of day and night

　　 4. The colors of the crab's skin can

　　　　   A. indicate the time

　　　　   B. prevent its enemies from noticing it

　　　　   C. prevent it from getting too hot

　　   D. do all the above

 

Answer 1

答案：C;C;D;D
解析：
    1．C。细节题。文章第一句说明生物自身的活动规律与大自然的节奏是一致的。通过例证，作者得出结论：生物钟的概念就是rhythmic patterns of activity in living things。由此得出结论，选项C与此内容是一致的。选项A中“大自然的节奏”、选项B中“昼夜的交替”及选项D中“生物活动的重复”都没有正确地把握住生物钟的定义。     2．C。细节题。在第三段第二句中，作者明确说明：This animal is a living clock(这种动物是一个活的钟)。因此，选项C正确。这里的living clock(有生命的，活的钟)和biological clock(生物钟)在概念的侧重点上有一定差异，因此选项A、B、D三项均不合题意。     3．D。细节题。第三段大意讲：蟹壳的颜色根据昼夜的时间交替产生变化，并且每24小时循环一次。这样一来，蟹的实验价值就体现出来，因为the alternating colors of the skin appear to follow the alternating rhythm of day and night(蟹壳的颜色交替变化似乎与昼夜交替变化的节奏一致)。选项D和上述内容完全一致，故选D。选项A和B与本文内容无关。选项C的内容虽然本文有所涉及，但它只是一个有待证明的假设，不是本题所 要求的原因。     4．D。细节题。选项A、B、C的内容在第三段第三、四句话中有明确的表达，因此选D正确。