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
58
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
A、Inagrocerystore.B、Inarestaurant.C、Inadepartmentstore.B
Whenwasthelasttimeyousawafrog?Chancesare,ifyouliveinacity,youhavenotseenoneforsometime.Eveninwetarea
Whatistheprobablerelationshipbetweenthetwospeakers?
ThefourthcomponentoftheSwedishsocialsystemisthatitspoliciesensurefullemploymentandincreasethemobilityoflabou
Warhasescapedthebattlefieldandnowcan,withmodemguidancesystemsonmissiles,touchvirtuallyeverysquareyardofthee
anxiousabout,strong,suggest,instruct,which,especial,whether,applyto,all,both,great,formWorkingouttomusicca
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。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)世界第二。(interms
【T1】身份盗用是指有人不当获取并使用他人的个人信息:如姓名、生日、驾驶证号码也包括信用卡、银行卡和电话号码信息等导致的犯罪。(referto)这种犯罪意味者欺诈,目的就是获取钱财。盗用身份者采取多种方式获取他人的个人信息,盗取他们的身份。近年来,
YYZZZYZZYisto221112112asYYZZYZZYisto______.
YYZZZYZZYisto221112112asYYZZYZZYisto______.
随机试题
Themodernstream-of-consciousnesstechniquewasfrequentlyandskillfullyexploitedby______toemphasizethereactionsandinn
任何一种态度都有其相对应的特定对象,这是指()
在慢性盘状红斑狼疮的病理诊断中正确的是
下列不属于高压部件的是
工程评标方法中,对“工程量清单报价范围、数量及算术错误”的评定,属于()评审因素和标准。
逐条判断部分工程施工机械的配置是否合理,如不合理,请改正。水泥混凝土路面施工主要机械设备有哪些?
股票按面值发行,被称为()。
甲公司为国内上市的电信公司。甲公司正在研究收购某发展中国家的乙移动通信公司。下列各项因素中,属于甲公司在PEST分析中应当考虑的有()。
下图是GIS案例分析示意图,图中的顺向坡面是指岩层倾斜方向与山坡方向相同。读图完成下列问题。该案例研究的主题是()。
TheMessagesinDistanceI.Peoplefromdifferentcultures【T1】________differentlyA.NorthAmericansstandabouttwofeetapa
最新回复
(
0
)