首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Birds that are literally half-asleep---with one brain hemisphere alert and the other sleeping- control which side of the brain r
Birds that are literally half-asleep---with one brain hemisphere alert and the other sleeping- control which side of the brain r
admin
2010-06-30
49
问题
Birds that are literally half-asleep---with one brain hemisphere alert and the other sleeping- control which side of the brain remains awake, according to a new study of sleeping ducks.
Earlier studies have documented half-brain sleep in a wide range of birds. The brain hemi- spheres take turns sinking into the sleep stage characterized by slow brain waves. The eye con- trolled by the sleeping hemisphere keeps shut, while the wakeful hemisphere’ s eye stays open and alert. Birds also can sleep with both hemispheres resting at once.
Decades of studies of bird flocks led researchers to predict extra alertness in the more vulnerable, end-or-the-row sleepers. Sure enough, the end birds tended to watch carefully on the side away from their companions. Ducks in the inner spots showed no preference for gaze direction.
Also, birds dozing(打盹) at the end of the line resorted to single-hemisphere sleep, rather than total relaxation, more often than inner ducks did. Rotating 16 birds through the positions in a four-duck row, the researchers found outer birds half-asleep during some 32 percent of dozing time versus about 12 percent for birds in internal spots.
"We believe this is the first evidence for an animal behaviorally controlling sleep and wakefulness simultaneously in different regions of the brain, "the researchers say.
The results provide the best evidence for a long-standing supposition that single-hemisphere sleep evolved as creatures scanned for enemies. The preference for opening an eye on the lookout side could be widespread, he predicts. He’s seen it in a pair of birds dozing side-by-side in the zoo and in a single pet bird sleeping by a mirror. The mirror-side eye closed as if the reflection were a companion and the other eye stayed open.
Useful as half-sleeping might be, it’s only been found in birds and such water mammals(哺乳动物) as dolphins, whales, and seals. Perhaps keeping one side of the brain awake allows a sleeping animal to surface occasionally to avoid drowning.
Studies of birds may offer unique insights into sleep. Jerome M. Siegel of the UCLA says he wonders if birds’ half-brain sleep “is just the tip of the iceberg (冰山)”. He speculates that more examples may turn up when we take a closer look at other species.
By “just the tip of the iceberg” (Line 2, Para. 8), Siegel suggests that _________.
选项
A、half-brain sleep has something to do with icy weather
B、the mystery of half-brain sleep is close to being solved
C、most birds living in cold regions tend to be half sleepers
D、half-brain sleep is a phenomenon that could exist among other species
答案
D
解析
转载请注明原文地址:https://kaotiyun.com/show/EVJd777K
本试题收录于:
公共英语四级笔试题库公共英语(PETS)分类
0
公共英语四级笔试
公共英语(PETS)
相关试题推荐
Humansareforeverforgettingthattheycan’tcontrolnature.Exactly20yearsago,aTimemagazinecoverstoryannouncedthat
EversinceGregorMendel’sfamousexperimentswithhybridsweetpeas,ithasbeenknownthattheremustbeunitaryelementswit
Onlythreestrategiesareavailableforcontrollingcancer:prevention,screeningandtreatment.Lungcancercausesmoredeaths
Onlythreestrategiesareavailableforcontrollingcancer:prevention,screeningandtreatment.Lungcancercausesmoredeaths
85%根据“Afterall,85percentofdoctorssupportexperimentsonanimals.”得出答案。句子中出现各类承接词时要特别注意,上下文往往是考点所在。
Anine-year-oldschoolgirlsingle-handedlycooksupascience-fairexperimentthatendsupdebunking(揭穿......的真相)awidelypract
Generallyspeaking,aBritishiswidelyregardedasaquiet,shyandconservativepersonwhois【21】______onlyamongthosew
随机试题
女性,22岁,因感冒发热1周后,出现眼痛、流泪和视物模糊。检查可见结膜充血、角膜点状浸润,荧光素着色阳性。最可能的诊断是
A.麻黄配杏仁B.麻黄配石膏C.麻黄配桂枝D.桂枝配白芍E.麻黄配细辛
清源公司将承建的建筑工程承包给无特种作业操作资格证书的司马过,司马过在操作时引发事故,中原省建设厅作出暂扣清源公司安全生产许可证三个月的决定,之后汉州市安全监督管理局又对清源公司罚款三万元。清源公司对汉州市安全监督管理局罚款不服,向法院起诉,下列选项是正确
债权债务的概括转移的条件包括()。
对于保管期满但未结清的债权、债务原始凭证和涉及其他未了事项的原始凭证.不得销毁,应单独抽出立卷,由档案部门保管到未了事项完结时为止。()
境外某电子产品制造公司为扩展中国业务,2011年初设立上海代表处作为常驻代表机构,主要从事与总公司产品销售、境内采购有关的联络活动以及中国市场调查、展示活动。2012年6月,主管税务机关进行税务检查时发现代表处账簿设置不健全,收入无法查实,但经费支出项目记
下列关于合同取得成本和合同履约成本的相关处理,表述不正确的是()。
透支作为一种信贷方式,是造成社会经济生活中信用膨胀、货币金融市场混乱的直接原因之一。如果银行是依靠其原来吸收的各种存款和储蓄来________透支,即不改变信用资金来源的数额而靠原来的贷款来实现透支,这种透支是有物质基础的,不会给货币市场造成太大的影响。实
给定程序中,函数fun的功能是:将参数给定的字符串、整数、浮点数写到文本文件中,再用字符串方式从此文本文件中逐个读入,并调用库函数atoi和atof将字符串转换成相应的整数、浮点数,然后将其显示在屏幕上。请在程序的下画线处填入正确的内容并把下画
Scientistsarelearningmoreaboutour【C1】______forsleep.Mostpeoplesleep【C2】______eighthourseachnight.【C3】______people
最新回复
(
0
)