Question

Doctors sometimes use light therapy to treat a form of depression in people who get too little morning sun. But too much light at other times may actually cause such mood disorder. Long-lasting exposure to light at night brings depression, a new study finds, at least in animals.

The new data confirm observations from studies of people who work night shifts, says Richard Stevens of the University of Connecticut Health Center. Mood disorders join a growing list of problems, including cancer, obesity and diabetes that can occur when light throws life out of balance by disturbing the biological clock and its timing of daily rhythms.

In the new study, Tracy Bedrosian and Randy Nelson of Ohio State University exposed mice to normal light and dark cycles for four weeks. For the next four weeks, half of the mice remained on this schedule, and the rest received continuous dim light throughout their night. Compared with mice exposed to normal night-time darkness, those getting dim light at night lost their strong preference for sweet drinks. “A sign that they no longer get pleasure out of activities they once enjoyed,” Bedrosian says.

In a second test, mice were clocked on how long they actively tried to escape a pool of water. Those exposed to night lights stopped struggling and just floated in the water, a sign of “behavioral despair”, 10 times as long as the mice that had experienced normal night-time darkness. All symptoms of depression disappeared within two weeks of the mice returning to a normal light-dark cycle, the researchers report. The scientists could also quash the behavioral symptoms by injecting the brains of animals with a drug that prohibits the activity of certain molecules linked with human depression. This finding further suggests that light at night may cause something related to depression.

Human studies linking night-time light and mood disorders are important but can not easily detect molecular underpinnings(分子基礎(chǔ)) as animal studies can, says George Brainard of Thomas Jefferson University. The new work, he says, suggests that the change of the biological clock by light at night can be “an extremely powerful force in regulating biology and behavior”.

1.After being exposed to continuous night-time light, the mice __________.

A. changed their preferences

B. escaped from the water more eagerly

C. remained active as before

D. showed less interest in their favorites

2.What does the underlined word “quash” in paragraph 4 probably mean?

A. study B. predict

C. ease D. cause

3.We can learn from the last paragraph that _______________.

A. light at night may have practical value

B. the biological clock is beneficial to humans

C. human mood disorders cannot be healed easily

D. human studies are more important than animal studies

4.What is the main idea of the passage?

A. Night-time light may cause depression.

B. A drug has been found to cure mood disorders.

C. The study on animals can be applied to humans.

D. Human biological clock can be controlled by light.

Answer 1

1.D

2.C

3.A

4.A

【解析】

試題分析：一項(xiàng)研究表明，至少在動(dòng)物身上，長時(shí)間暴露于夜晚的光線會(huì)帶來沮喪，并用小白鼠進(jìn)行試驗(yàn)論證。

1. with mice exposed to normal night-time darkness, those getting dim light at night lost their strong preference for sweet drinks.句意：與暴露在正常的夜晚黑暗中的小白鼠相比，那些在夜晚得到昏暗燈光的小白鼠失去了對天的飲料的強(qiáng)烈偏好。得知此類小白鼠的偏好會(huì)受光照改變。故選D

2. scientists could also quash the behavioral symptoms by injecting the brains of animals with a drug that prohibits the activity of certain molecules linked with human depression句意：科學(xué)家們也能通過像動(dòng)物大腦注射一種藥物來消除這種行為性癥狀，這種藥物會(huì)阻止某些和人類沮喪相聯(lián)系的分子運(yùn)動(dòng)。以及上一句中All symptoms of depression disappeared…所有的沮喪癥全部消失了……得知這里quash在與ease意思相近：使無效，平息。故選C

3. 對人類的關(guān)于夜晚光線和情緒紊亂的研究很重要，但是卻不能像對動(dòng)物的研究那么容易的探測到分子基礎(chǔ)，Tomas Jefferson大學(xué)的George Brainard說道。他說，新的工作暗示著由夜晚光線導(dǎo)致的生物鐘的改變可能是“在調(diào)控生物學(xué)和行為學(xué)方面非常有力的力量”。得知其強(qiáng)調(diào)的是light at night may have practical value夜晚的光線有特殊的作用，故選A

4. exposure to light at night brings depression, a new study finds, at least in animals(一項(xiàng)研究表明，至少在動(dòng)物身上，)，以及第四段最后一句This finding further suggests that light at night may cause something related to depression（這種發(fā)現(xiàn)進(jìn)一步表明夜晚的光線會(huì)導(dǎo)致和沮喪相關(guān)的事情）。故選A

考點(diǎn)：考查科學(xué)實(shí)驗(yàn)類說明文閱讀。