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
41
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.
Most bacteria used in medicine and industry grow best between the temperature of 20 °F and 45°F.
选项
A、TRUE
B、FALSE
答案
B
解析
(文章第三段最后一句话明确指出Most bacteria used in medicine and industry grow best between 20℃and 45℃。)
转载请注明原文地址:https://kaotiyun.com/show/dSAK777K
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
Nuclearpowerplantsaresomeofthelargestproducersof______wastes,witheachplantproducingbarrelsofradioactivemateri
Whatistheincreasebetweenthetwoanti-smokingcampaigns?
Whichofthewords,AtoD,ismissingfromthebrackets?BEND(LOOPHOLE)LAIRHALT(……)LEAF
Iwishyou’dmetmyUncleBill.Hewasatallman--sotallthathecouldchangethebulbsinlightsocketswhilehardlyreaching
Normallyastudentmustattendacertainnumberofcoursesinordertograduate,andeachcoursewhichheattendsgiveshimacr
NewYear’sDayisonFriday.ThreedaysaftertomorrowisNewYear’sDay.Whichofthefollowingstatementsmustbetrue?
Whenwasthelasttimeyousawafrog?Chancesare,ifyouliveinacity,youhavenotseenoneforsometime.Eveninwetarea
TheMillenniumSeedBankProjectOneofthelargestconservationprojectseverundertaken;thisinternationalcollaboration
anxiousabout,strong,suggest,instruct,which,especial,whether,applyto,all,both,great,formWorkingouttomusicca
YYZZZYZZYisto221112112asYYZZYZZYisto______.
随机试题
证明:当1<x<2时,4xlnx>x2+2x-3.
下列可引起头痛伴剧烈眩晕的是
关于技术,下列说法正确的是()。
施工单位从事建设工程的施工,必须拥有()。
发行人募集资金投资项目分析可以不在投资价值研究报告中反映。()
(节选)(2017年)甲公司为居民企业……甲公司的下列收益中,在计算2016年度企业所得税应纳税所得额时,应计入收入总额的是()。
根据有关规定,实施义务教育的普通学校应当接收具有接受普通教育能力的残疾适龄儿童、少年()。
下列问诊内容正确的是()。
Mondayisbeginningoftheworkweek:it’s【C1】______daymostpeoplelike【C2】______.It’snot【C3】______thatthedaytheylikemost
A、AfitnessgymB、Atenniscourt.C、Aswimmingpool.D、Atabletennisroom.C本题询问这位女士感兴趣的运动设备。根据对话中女士的问话Doyouhaveaswimmingp
最新回复
(
0
)