首页
登录
职称英语
The livelihood of each species in the vast and intricate assemblage of livin
The livelihood of each species in the vast and intricate assemblage of livin
游客
2025-04-06
11
管理
问题
The livelihood of each species in the vast and intricate assemblage of living things depends on the existences of other organisms. This interdependence is sometimes subtle, sometimes obvious. Perhaps the most straightforward dependence of one species on another occurs with parasites, organisms that live on or in other living things and derive nutrients directly from them. The parasitic way of life is widespread. A multitude of microorganisms(including viruses and bacteria)and an army of invertebrates—or creatures lacking a spinal column(including crustaceans, insects, and many different types of worms)make their livings directly at the expense of other creatures. In the face of this onslaught, living things have evolved a variety of defense mechanisms for protecting their bodies from invasion by other organisms.
Certain fungi and even some kinds of bacteria secrete substances known as antibiotics into their external environment. These substances are capable of killing or inhibiting the growth of various kinds of bacteria that also occupy the area, thereby eliminating or reducing the competition for nutrients. The same principle is used in defense against invaders in other groups of organisms. For example, when attacked by disease-causing fungi or bacteria, many kinds of plants produce chemicals that help to ward off the invaders.
Members of the animal kingdom have developed a variety of defense mechanisms for dealing with parasites. Although these mechanisms vary considerably, all major groups of animals are capable of detecting and reacting to the presence of "foreign" cells. In fact, throughout the animal kingdom, from sponges to certain types of worms, shellfish, and all vertebrates(creatures possessing a spinal column), there is evidence that transplants of cells or fragments of tissues into an animal are accepted only if they come from genetically compatible or closely related individuals.
The ability to distinguish between "self" and "nonself", while present in all animals, is most efficient among vertebrates, which have developed an immune system as their defense mechanism. The immune system recognizes and takes action against foreign invaders and transplanted tissues that are treated as foreign cells. [br] What does the passage mainly discuss?
选项
A、How parasites reproduce.
B、How organisms react to invaders.
C、How antibiotics work to cure diseases.
D、How the immune system of vertebrates developed.
答案
B
解析
短文主要讨论什么?生物如何对入侵者作出反应。第一段末句指出,生物逐渐形成各种各样的防御机制,以便使身体免受其他生物的侵害。二、三、四段着重证明生物如何对入侵者作出反应。
转载请注明原文地址:https://tihaiku.com/zcyy/4028646.html
相关试题推荐
Coincidentwithconcernsabouttheacceleratinglossofspeciesandhabitats
Coincidentwithconcernsabouttheacceleratinglossofspeciesandhabitats
Coincidentwithconcernsabouttheacceleratinglossofspeciesandhabitats
Thetimberrattlesnakeisnowontheendangeredspecieslist,andisextinctin
Manyspeciesofanimalswhichoncelivedontheeartharenolongerin______.A、
Therearedifferent______ofbooksinalibrary.(2007年中国矿业大学考博试题)A、speciesB、bio
Inancienttimes,somecatastrophicextinctionofspeciesoccurred______.(2004年武
Pigeonisthecommonnameformembersofafamilyofbirds;smallerspeciesare
Shouldwecareifover150knownspeciesofanimalshave【C1】______fromthee
Shouldwecareifover150knownspeciesofanimalshave【C1】______fromthee
随机试题
关于著作权,说法正确的有( )。A.著作权也称版权 B.未发表的作品不享有著
Text3OliviaPedersenthoughttheNissa
A. B. C. D.
女性,26岁,痛经3年,进行性加重,经量无明显增加,经期延长了2~3天,已婚3年
临床疑为DIC,应选择下列哪组筛选试验A.PT、APTT、血小板计数 B.血小
投资机会研究分为一般投资机会研究和()。A、详细研究 B、粗略研究 C
马克思主义之所以具有与时俱进的品格是因为( ) A.它是一个开放的体系 B
内环境包括A.组织液 B.血浆 C.消化液 D.淋巴液
主治风热咳嗽的中成药有A.急支糖浆 B.橘红丸 C.川贝止咳露 D.蛇胆川
男,50岁。右下后牙冷酸食及刷牙时酸痛感,刺激去除后酸痛感立即消失。检查:右下颌
最新回复
(
0
)