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
(1)We have all been instructed to wash our hands before eating to avoid ingesting "germs." Microorganisms(bacteria, protozoa, an
(1)We have all been instructed to wash our hands before eating to avoid ingesting "germs." Microorganisms(bacteria, protozoa, an
admin
2021-08-05
60
问题
(1)We have all been instructed to wash our hands before eating to avoid ingesting "germs." Microorganisms(bacteria, protozoa, and yeast)seem to have a bad reputation when it comes to food! The nasty ones make headlines and the TV news, and some cause us a little discomfort. But this downside of germs is not the whole story! Beneficial microbes far outnumber the harmful(pathogenic)ones, and we depend on all their good deeds for our nutritional well-being and health! It’s high time the "good" bacteria get the credit they deserve!
(2)We all prefer to think of ourselves as individuals, but it would be much more accurate if we pictured ourselves as thriving communities! Right now, there are more microbes living on you than there are cells in your body! Of course, they are not actually part of you, but the bacteria alone add up to approximately 10 percent of your dry weight(you minus the water)! Microorganisms may be small, but their numbers make up for their size.
(3)On every surface of your body there are tiny microbes going about their business. The surface of the digestive system takes the award for the largest population—by far—of microorganisms. Here, their numbers reach astronomical proportions. More individuals of the bacterial species Escherichia coli will inhabit your intestine during your lifetime than the number of people who have ever lived on the Earth! E. coli is but one of the 400 or so species that are common members of the intestinal community. A few yeast and protozoa species top off the list.
(4)But wait! Not to worry! This may seem like a creepy, crawly mess, but the majority of your intestinal microorganisms are not nasty intruders. They are important and invited guests: your personal microbes. As well as helping you to digest and process your food and providing you with essential vitamins, they make it their business also to protect you against those nasty sorts. All of this, simply in exchange for food, warmth, and a space to multiply!(This kind of relationship in which everyone benefits is called mutualism.)As long as this arrangement is functioning properly, you remain largely unaware of your microbes and their business. But when it is not—that’s another story!
(5)The microbes of your large intestine make their living by breaking down the discards of the small intestine, material that your human system has rejected as indigestible. Equipped with their own set of enzymes and metabolic pathways, they proceed to further tear apart the organic compounds that remain. Most of them get to work disassembling the plant carbohydrates. The majority of microbes of the large intestine are anaerobic, meaning that they live in the absence of oxygen. Instead of breathing in and out, they are able to derive all of their energy by splitting large carbohydrates into smaller fatty acid molecules and carbon dioxide, in a process known as fermentation.
(6)Some of the fatty acids are reabsorbed through the intestinal walls, providing us with a bonus energy source. The rest help me bacteria to grow rapidly, rapidly enough to reproduce themselves as often as every twenty minutes! Synthesizing more of some of the B vitamins and vitamin K than they need for their own growth, they kindly make the surplus available to other creatures in their community, and to you, their host. Although you are unable to manufacture these vitamins yourself, you can count on your friendly microbes for an unfailing supply.
(7)Scientists are just beginning to understand the complex relationships between the different microorganisms of this community and their interactions with a human host. It is a dynamic system, which constantly adjusts to a host’s changes in age and diet. Right after your birth, you begin to assemble your own select group of species. As your diet moves from mother’s to cow’s milk and then to different solid foods, new species dominate the population.
(8)Microbes that colonize the walls of the large intestine are survivors of a very difficult journey! From the mourn through the small intestine, they are attacked by digestive enzymes and strong acids. Those mat complete the trip intact face more obstacles on their arrival. To grow, they must compete successfully with those already there for room and nutrients. Fortunately, the "friendly" bacteria are very adept at gluing themselves to most of the available wall space! Some of these friendly bacteria can produce acids and antibacterial compounds known as "bacteriocins," which help to discourage invasion by the unsavory types. The sheer numbers of "good" bacteria usually prevent the "nasties" from gaining a "foothold" before passing on their way unnoticed.
The majority of the microbes in the human body live _____.
选项
A、on the surface of our skin
B、on the surface of the digestive system
C、by breaking down indigestible materials
D、by disassembling me plant carbohydrates
答案
B
解析
第3段第2句提到,在消化系统的表面细菌的数量是最多的,故B对。A与第3段的表述不符;C、D是文章对大肠中的细菌的描述,而不是大部分细菌的情况,属于以偏概全,故错误。
转载请注明原文地址:https://kaotiyun.com/show/3JIK777K
0
专业英语八级
相关试题推荐
Abroadpublicdiscussionofenvironmentalproblemsbeganinthemid-1980s,whenthefirst"green"groupsformedinopposition
Ineveryeconomicsystem,entrepreneursandmanagersbringtogethernaturalresources,labor,andtechnologytoproduceanddi
Ineveryeconomicsystem,entrepreneursandmanagersbringtogethernaturalresources,labor,andtechnologytoproduceanddi
Withtheeffectsofglobalization,increasesintechnologyandthepaceoflifeinvademoreandmoreareasofeverydaylife,an
Humanity’shighlydevelopedabilitytocommunicateverballyisouressence.Withourtremendousvocabulary,wewouldperhapsbe【
Humanity’shighlydevelopedabilitytocommunicateverballyisouressence.Withourtremendousvocabulary,wewouldperhapsbe【
Secondlanguageteachingshouldfocusonencouragingacquisition,andonprovidinginputthatstimulatestheconscious【S1】______
TheUnitedStatesisconsideredamultilingualcountrybutithasneveremployedanofficiallanguagepolicy.EventhoughEngl
Individualsareincreasinglybeingaskedtotakeonsoleresponsibility—andassumetheburdenofrisk—forcomplexsavingstasks
随机试题
IntheUnitedStatesandCanada,aprom,shortforpromenade,isaformaldance,orgettingtogetherofhighschoolstudents.It
属于广谱类抗病毒的药物是:
患者,女,50岁,体重60kg。因反复呕吐5天入院。血清钠130mmol/L。入院当天应补充的钠量是()
黏膜局部抗感染的重要因素惟一可通过胎盘的抗体
药品作为特殊商品,其特殊性之一是具有两重性,而两重性主要体现在( )
A、AgNO3硅胶柱色谱B、60%~65%H3PO4C、吉拉尔试剂D、氧化铝柱色谱E、硅胶柱色谱分离α-细辛醚和β-细辛醚用()
甲为了能在自己的房子里欣赏远处的风景。便与相邻的乙约定:乙不在自己的土地上从事高层建筑;作为补偿,甲每年支付给乙3000元。两年后,乙将该土地使用权转让给丙。丙在该土地上建了一座高楼,与甲发生了纠纷。对此纠纷,下列判断正确的是()。
ABC会计师事务所负责审计D集团公司2014年度财务报表,并委派A注册会计师担任审计项目合伙人。D集团公司属于家电制造行业,共有4家全资子公司,各子公司的相关资料摘录如下。要求:假定在确定某子公司对集团而言是否具有财务重大性时,A注册会计师采用资产
面向管理的计算机应用系统中,如果系统的处理对象是专门解决不确定或不完全信息的推理,这通常属于
WheredoesTomlive?
最新回复
(
0
)