首页
登录
职称英语
Plants are subject to attach and infection by a remarkable variety of symbio
Plants are subject to attach and infection by a remarkable variety of symbio
游客
2025-03-27
17
管理
问题
Plants are subject to attach and infection by a remarkable variety of symbiotically species and have evolved a diverse array of mechanisms designed to frustrate the potential colonists. These can be divided into preformed or passive defense mechanisms and inducible or active systems. Passive plant defense comprises physical and chemical barriers that prevent entry of pathogens(病原体), such as bacteria, or render tissues unpalatable or toxic to the invader. The external surfaces of plants, in addition to being covered by an epidermis(表皮层) and a waxy cuticle, often carry spiky hairs known as trichomes(毛状物), which either prevent feeding by insects or may even puncture and kill insect larvae. Other trichomes are sticky and glandular and effectively trap and immobilize insects.
If the physical barriers of the plant are breached, then preformed chemicals may inhibit or kill the intrude, and plant tissues contain a diverse array of toxic or potentially toxic substances, such as resins, tannins, glycosides, and alkaloids, many of which are highly effective deterrents to insects that feed on plants. The success of the Colorado beetle in infesting potatoes, for example, seems to be correlated with its high tolerance to alkaloids that normally repel potential pests. Other possible chemical defenses, while not directly toxic to the parasite, may inhibit some essential step in the establishment of a parasitic relationship. For example, glycoproteins(糖蛋白) in plant cell walls may inactivate enzymes that degrade cell walls. These enzymes are often produced by bacteria and fungi.
Active plant defense mechanisms are comparable to the immune system of vertebrate animals, although the cellular and molecular bases are fundamentally different. Both, however, are triggered in reaction to intrusion, implying that the host has some means of recognizing the presence of a foreign organism. The most dramatic example of an inducible plant defense reaction is the hypersensitive response. In the hypersensitive response, cells undergo rapid necrosis—that is, they become diseased and die—after being penetrated by a parasite; the parasite itself subsequently ceases to grow and is therefore restricted to one or a few cells around the entry site. Several theories have been put forward to explain the basis of hypersensitive resistance. [br] Which of the following substances does the author mention as NOT necessary being toxic to the Colorado beetle?
选项
A、Resins
B、Tannins
C、Glycosides
D、Alkaloids
答案
D
解析
依据文章第二段,“The success of the Colorado beetle in infesting potatoes, for example, seems to be correlated with its high tolerance to alkaloids”那种侵扰西红柿的害虫,对alkaloids有很强的忍耐性,D项不一定对它有毒。
转载请注明原文地址:https://tihaiku.com/zcyy/4015125.html
相关试题推荐
Botany,thestudyofplants,occupiesapeculiarpositioninthehistoryof
Botany,thestudyofplants,occupiesapeculiarpositioninthehistoryof
Botany,thestudyofplants,occupiesapeculiarpositioninthehistoryof
Botany,thestudyofplants,occupiesapeculiarpositioninthehistoryof
Plantsaresubjecttoattachandinfectionbyaremarkablevarietyofsymbio
Plantsaresubjecttoattachandinfectionbyaremarkablevarietyofsymbio
Plantsaresubjecttoattachandinfectionbyaremarkablevarietyofsymbio
ThedesiretospeakgoodEnglishhasdriventhesechildrentomakearemarkable
Chinahasseenremarkableimprovements______thegloom______globalwarming.A、amid
Man:Wouldyouliketohavesomeicecream?I’vegotavarietyofflavors.Woman:
随机试题
Pollutionoccurswheneverunnaturalsubstancesareintroducedintoanenvir
[originaltext]M:Hello.ThisisGregRicereportingliveinBarrow,Alaska.W:
[originaltext]AnewbookbytwoprofessorsatPennsylvaniaStateUniversity
[originaltext]W:WhydidJackfailintheexam?M:Ifhehadstudiedhard,hew
王老师执教《中国画写意花鸟——梅兰竹菊》一课时,将“中国画‘托物言志’的艺术特征
在基坑开挖过程中出现渗水,采用方法及时处理的主要依据是()。A、开挖方式 B、
儿童最常见的急性白血病类型是A.急性淋巴细胞白白血病 B.急性粒细胞白血病
教育是人类社会和动物界共有的现象,与人类几乎是同时产生的。()
关于组织承诺的陈述,正确的是()。A.情感承诺高的员工会表现出较高的工作满意度
根据建设项目法人责任制,新建项目正式成立项目法人的时间要求是()。A.申报项目
最新回复
(
0
)