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
Most people consider bacteria dangerous. After all, these microorganisms cause a host of serious human diseases, including tuber
Most people consider bacteria dangerous. After all, these microorganisms cause a host of serious human diseases, including tuber
admin
2016-01-14
45
问题
Most people consider bacteria dangerous. After all, these microorganisms cause a host of serious human diseases, including tuberculosis, typhoid fever, pneumonia, and food poisoning. In fact, however, only a small percentage of bacteria cause diseases, while many bacteria are actually beneficial to humans. For example, doctors use bacteria to produce vaccines and other medicines.
Bacteria are also critical to many industrial processes, from fermenting wine to recycling wastes, and scientists use bacteria to study many of the biological processes common to all living things.
With such a wide variety of economic and scientific applications, it is no surprise that several laboratories around the United States grow and sell bacteria as a crop. These laboratories use specialized farming techniques to produce one of the nation’ s most valuable biological commodities.
Like plants, bacteria have specific growth requirements. In particular, they need a place to grow and they need a supply of nutrients. Bacteria may be cultivated in containers ranging from small test tubes to giant steel tanks. The organisms are placed in a container along with a nutritionally balanced liquid or jelly, called a culture medium, which provides vitamins, minerals, and fluids to the growing bacteria. The growth container and culture medium must be kept at a constant temperature that is appropriate for the type of bacteria being cultivated. Most bacteria used in medicine and industry grow best between 20℃ and 45℃.
In a closed container, bacteria exhibit a definite growth pattern. The figure shows a typical bacterial growth curve. All bacteria follow this pattern, a fact that is very important to anyone who wants to cultivate them in large numbers.
When bacteria are first placed in a growth container, they must adapt to their new environment, and growth is slow while they are making this adjustment.
This period is called the " start phase" of the bacterial growth cycle. At the end of this phase, as the bacteria become accustomed to their new living conditions, they begin to grow and reproduce rapidly. During the second phase, called the "log phase," a population explosion occurs. In a large tank, millions of new bacteria may be produced every hour during this phase. Eventually, however, the bacterial population reaches the maximum size possible, given the limitations of the growth container. At this point, the bacteria enter the " stationary growth phase," during which they continue to reproduce, but at a slower rate. After a time, the bacteria use up their supply of nutrients and their wastes accumulate in the growth container. The final period in the growth cycle, called the "death phase," occurs when the bacteria begin to die faster than they reproduce.
People who grow bacteria for science and industry take advantage of this unique growth cycle. Bacteria are harvested during the " stationary growth phase," yielding a good crop of usable organisms. By carefully monitoring the growth pattern, bacteria farmers can also decide when to add more nutrients to the culture medium or to transfer the bacteria to new growth containers. In this way, they can prevent large losses during the "death phase. " By applying a knowledge of the growth requirements and patterns of bacteria, these modern-day agriculturalists are able to help everyone derive the maximum benefit from these versatile organisms.
Bacteria are also critical to many industrial processes, from fermenting wine to recycling wastes, and scientists use bacteria to study many of the biological processes common to all living things.
选项
答案
对很多工业流程,例如葡萄酒酿造和工业废料再循环来说,细菌是至关重要的因素。并且科学家还可以通过细菌来研究所有生物共有的生物进程。
解析
(本句句子拆分法,转换主语,使表达更符合中文习惯。fermenting wine酿造葡萄酒。)
转载请注明原文地址:https://kaotiyun.com/show/ZSAK777K
本试题收录于:
B类竞赛(英语专业本科专科)题库大学生英语竞赛(NECCS)分类
0
B类竞赛(英语专业本科专科)
大学生英语竞赛(NECCS)
相关试题推荐
IntheUnitedStatesalsothereweregreatchanges,thoughthecauseshereweredueonlyinparttothewar;theysprangmainly
JamesandTomlikerugby.TimandNicholaspreferfootball.OnlyNicholasdoesnotenjoyrollerskating.Whichofthefollowing
Normallyastudentmustattendacertainnumberofcoursesinordertograduate,andeachcoursewhichheattendsgiveshimacr
Whatistheprobablerelationshipbetweenthetwospeakers?
100mphgalescausechaos【76】Strongwinds,whichattimesreachedspeedsof100mph,broughthavoctomanypartsofBritain
Theideaofafishbeingabletogenerateelectricitystrongenoughtolightlampbulbs—oreventorunasmallelectricmotor—is
ThisWednesday,GordonBrownwillreplaceTonyBlairasthenewheadofBritain’sLaborParty.Thislong-servingchancellorisa
中国经济发展潜力大、优势足、空间广,前景光明。【T1】我们有9亿多劳动力,其中1.7亿多受过高等教育或有专业技能。(非限制性定语从句)每年大学毕业生700多万,中职毕业生500多万。【T2】科技人员数量世界第一,研发投入(R&Dinput)世界第
据悉,自1986年起,美国华人经济已跃居全美少数民资之首,遥遥领先与日裔、韩裔等其他后裔。美国华人家庭的年均收收入应经超过美国白人家庭。(leapto)
(81)具体说,信息化主要是反映在沟通手段的网络化,也就是所谓的网络经济。这网络就是指由卫星、光纤、电缆和电话线路把世界各个角落联系到一起的电脑网络。(82)只要用鼠标一点,在地球另一端的信息马上就会以每秒钟绕地球七周半的光速跑到你的电脑荧光屏上。
随机试题
()不发生财产所有权的转移。
1211灭火器主要用于易燃、可燃液体、气体、带电设备的初期火灾,()对木、纸、织物等物表面初期火灾进行扑救。
关于"传囊之变"的意义,下列哪项是正确的
A.α受体阻滞剂B.β受体阻滞剂C.钙拮抗剂D.利尿剂E.血管紧张素转化酶抑制剂治疗高血压伴心率过快,应首选
原发性肝癌与肝硬化的鉴别,下列哪项有利于前者的诊断
某工程项目合同工期为18个月。施工合同签订以后,施工单位编制了一份初始网络计划,如图8-2所示。由于该工程施工工艺的要求,计划中工作C、工作H和工作J需共用一台起重施工机械,为此需要对初始网络计划作调整。工作G完成后,由于业主变更施工图纸,使工作I
依据《通用安装工程工程量计算规范》(GB50856-2013),燃气管道工程量计算时,管道室内外界限划分为()。
北方光源中心的机电工程由某安装公司承包,工程内容有空调工程,仪表工程,光缆工程,BA系统及消防工程。空调系统的洁净度等级设计为N5级,并由BA监控,其传感器、执行器通过DDC与计算机连接。中心的门禁系统采用可以记录员工进出时间的非接触式感应电控锁。仪表设备
“教”“育”两个单字结合在一起作为一个词最早见于()。
Paulsuggestedthat(theymeet)(inthefrontof)theschoolgate(at)oneo’clock(Fridayafternoon).
最新回复
(
0
)