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
Bacteria Bacteria are extremely small living things. While we measure our own sizes in inches or centimeters, bacterial size
Bacteria Bacteria are extremely small living things. While we measure our own sizes in inches or centimeters, bacterial size
admin
2011-01-05
62
问题
Bacteria
Bacteria are extremely small living things. While we measure our own sizes in inches or centimeters, bacterial size is measured in microns. One micron is a thousand of a millimeter: a pinhead is about a millimeter across.
Rod-shaped bacteria are usually from two to four microns long, while rounded ones are generally one micron in diameter. Thus if you enlarged a rounded bacterium a thousand times, it would be just about the size of a pinhead. An adult human magnified by the same amount would be over a mile (1. 6 kilometers) tall. Even with an ordinary microscope, you must look closely to see bacteria. Using a magnification of 100 times, one finds that bacteria are barely visible as tiny rods or dots. One cannot make out anything of their structure. Using special stains, one can see that some bacteria have attached to them wavy-looking " hairs" called flagella. Others have only one flagellum. The flagella rotate, pushing the bacteria through the water. Many bacteria lack flagella and cannot move about by their own power, while others can glide along over surfaces by some little-understood mechanism.
From the bacterial point of view, the world is a very different place from what it is to humans. To a bacterium water is as thick as molasses is to us. Bacteria are so small that they are influenced by the movements of the chemical molecules around them. Bacteria under the microscope, even those with no flagella, often bounce about in the water. This is because they collide with the water molecules and are pushed this way and that. Molecules move so rapidly that within a tenth of a second the molecules around a bacterium have all been replaced by new ones; even bacteria without flagella are thus constantly exposed to a changing environment.
Bacteria are harmful for our health.
选项
A、Right
B、Wrong
C、Not mentioned
答案
C
解析
文章只是介绍细菌的外形、运动方式等,并未论及它与人体健康的关系。
转载请注明原文地址:https://kaotiyun.com/show/nlmd777K
本试题收录于:
职称英语卫生类A级题库职称英语分类
0
职称英语卫生类A级
职称英语
相关试题推荐
Idon’trecommendhiringskisatthisshop.advisableIt’s____________________skisatthisshop.
MOUNTAINCLIMBINGOneofthemostdifficultbutrewardingofpastimesisthesportofmountainclimbing.Mountainclimbing
Youaregoingtoreadamagazinearticleaboutthepopularityofactivityholidays.Choosethemostsuitableheadingfromtheli
A、Sunflowersissellingexerciseequipmenttomembersataspecialprice.B、Youwillqualifyforagiftifyoupersuadeafriend
Youwillhearsomeinformationaboutavisitortoaschool.Listenandcompletequestions21-25.Youwillheartheinformationt
ListentoSarahtalkingtoafriendaboutasportscentre.Whatistheproblemwiththedifferentthingsatthesportscentre?F
StressCanMakeYouSickScientistsarenowstudyinganewfieldofresearchwhichiscalledpsychoimmunology(心理免疫学).Itisb
AAddressingaVarietyofBehavior-affectingFactorsBImportanceofImmunizationCRelationshipwithOtherHealthServicesD
Awell-designedkitchenshouldbemodern,beautifulandpracticalatthesametime.Beingharmlesstotheenvironmentistheto
TheMeaningofDreams1Dreamsplayanimportantroleinourlives.Iftheycanbecorrectlyinterpreted,wecancometounderst
随机试题
引起菌群失调症的厌氧菌是()
下列描述中,不属于“新常态”下中国经济特征表现的是:
1945年昆明“一二·一”运动,吹响了国统区爱国学生运动的第一声号角,在全国范同产生了重大影响。它的基本口号是()
Wecanmakemistakesatanyage.Somemistakeswemakeareaboutmoney.Butmostmistakesareaboutpeople."DidJerryreallyca
根管最狭窄的地方在
下列是牙源性角化囊肿易复发的原因,除了()
患者,女性,43岁。胆囊结石病史3年,主诉晚餐后突然出现右上腹阵发性剧烈疼痛,向右肩、背部放射,伴有腹胀、恶心、呕吐等症状。体检示:体温38.9℃,脉搏112次/分,血压106/85mmHg。右上腹部有压痛、肌紧张、反跳痛。实验室检查:WBC10.5×1
征收城市郊区的菜地,用地单位应当按照国家有关规定缴纳()。
比较法是施工成本分析的基本方法之一,其常用的比较形式是()。
在西柏坡时期,中共中央:①召开了党的七届二中全会;②组织指挥了辽沈、淮海、平津三大战役;③领导了解放区的土改运动。上述历史事件出现的先后顺序是()。
最新回复
(
0
)