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
专升本
Bacteria are extremely small living things. While we measure our own sizes in inches or centimeters, bacterial size is measured
Bacteria are extremely small living things. While we measure our own sizes in inches or centimeters, bacterial size is measured
admin
2021-11-04
9
问题
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 thousandth of a millimeter; a pinhead is about a millimeter across. Rod-shaped bacteria are usually 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 (鞭毛). 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 (分子) 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 Molecules move so rapidly that within a tenth of a second the molecules around a bacterium have all been replaced by new ones.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.
The author compares water to molasses in order to show________.
选项
A、how difficult it is for bacteria to move through the water
B、how different the bacterial world is from the human world
C、how the water molecules work
D、what different bacteria one liquid contains from another
答案
A
解析
由文章第三段前三句可知作者将水比作糖浆是为了说明“水对于细菌来说就相当于糖浆对于人类一样稠,所以细菌在水中运动起来就很困难”,故选A。
转载请注明原文地址:https://kaotiyun.com/show/lfZC777K
本试题收录于:
英语题库成考专升本分类
0
英语
成考专升本
相关试题推荐
Inancienttimeswealthwasmeasuredandexchangedinthingsthatcouldbetouched:food,tools,andpreciousmetalsandstones.
Thestrangecloseunderstandingbetweentwinsisafamiliarenoughphenomenon.Oftentheyseemtounderstandeachotherandshar
A.WhatshouldIdoB.Thankyou,momC.WherehaveyoubeenD.Yes,heisE.WhatwaswrongwithhimF.WereyousickG.Where
A.WhatshouldIdoB.Thankyou,momC.WherehaveyoubeenD.Yes,heisE.WhatwaswrongwithhimF.WereyousickG.Where
—Whoaremakingsomuchnoiseinthegarden?—______thechildren.
Juliaisalwayssayingthatshecannot______beinglaughedat.
They______inspiteoftheextremelydifficultconditions.
It’sessentialthateverychild______thesameeducationalopportunities.
IftheEuropeansthoughtadrought—alongperiodofdryweather—wassomethingthathappenedonlyinAfrica,theyknowbetternow
随机试题
自感系数与线圈的()无关。
A.平胃散B.黄连解毒汤C.茵陈蒿汤D.白虎汤E.犀角地黄汤治疗阳明经证或气分实热选()。
SAC沥青混凝土路面施工中,填料为水泥或消石灰石粉或掺加抗剥落剂的沥青混合料的终压温度应不低于()。
出口危险货物包装容器,经检验合格的,检疫局出具出口危险货物包装性能检验证书。
()是指交易对方未能履行义务而造成经济损失的风险。
材料一“创客”源于英文单词“Maker”,“创客教育”即STEAM教育,始于美国,是Science(科学)、Technology(技术)、Engineering(工程)、Arts(艺术)、Mathematics(数学)的缩写,是包容性很强的跨学科综
根据下列资料,回答下列小题:我国2013年全年研究生招生61万人,在学研究生179万人,毕业生51万人。普通本专科招生700万人,在校生2468万人,毕业生639万人。中等职业教育招生698万人,在校生1960万人,毕业生678万人。普通高中招生823万
按照联合国开发计划署2007年的统计,挪威是世界上居民生活质量最高的国家,欧美和日本等发达国家也名列前茅。如果统计1990年以来生活质量改善最快的国家,发达国家则落后了。至少在联合国开发计划署统计的116个国家中,17年来,非洲东南部国家莫桑比克的生活质量
[*]
以下叙述中错误的是()。
最新回复
(
0
)