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
Lichens. probably the hardiest of all plants, live where virtually nothing else can---not just on rugged mountain peaks but
Lichens. probably the hardiest of all plants, live where virtually nothing else can---not just on rugged mountain peaks but
admin
2005-01-30
49
问题
Lichens. probably the hardiest of all plants, live where virtually nothing else can---not
just on rugged mountain peaks but also on sunbaked desert rocks. They are usually the
first life to appear on a mountainside that has been scraped bare by an avalanche.
Unlike other members of the plant kingdom, lichens are actually a partnership between
5 two plants. The framework of a lichen is usually a network of minute hairlike fungus that
anchors the plant, The other component is an alga (similar to the green film of plant life
that grows on stagnant pools) that is distributed throughout the fungus. Being green plants,
algae are capable of photosynthesis--that is, using energy from the Sun to manufacture
their own food. The fungi arc believed to supply water, minerals, and physical support to
10 the partnership.
Lichens are famous for their ability to survive ~ water shortage. When water is scarce
(as is often the case on a mountain), lichens may become dormant and remain in that
condition for prolonged periods of time. Some lichens can even grow where there is no
rain at all, surviving on only occasional dew--the moisture that condenses on the surface
15 of the plants at night, And unlike most other plants, lichens are little affected by the strong
ultraviolet rays in the mountains.
Lichens use little energy, for they grow slowly. Some grow so slowly and are so old
that they are called "time stains." You may find lichens that are centuries old; certain of
these lichen colonies have been established for an estimated 2,000 years.
20 For decades, scientists wondered how the offspring of an alga and a fungus got together
to form a new lichen, it seemed unlikely that they would just happen lo encounter one
another. It was finally discovered that in many cases the two partners have never been
separated. Stalklike "buds" that form on certain lichens are broken off by the wind or by
animals; these toll or are blown to a new location
选项
A、Where can the oldest lichens be found?
B、How long does it take for lichens to establish themselves?
C、How large can lichens he?
D、Where do lichens usually occur?
答案
D
解析
转载请注明原文地址:https://kaotiyun.com/show/z6yO777K
0
托福(TOEFL)
相关试题推荐
ChooseTWOletters,A-E.Writethecorrectlettersinboxes7and8onyouranswersheet.WhichTWOpositivefunctionsaboutMin
LivingDunesWhenyouthinkofasanddune,youprobablypictureabarrenpileoflifelesssand.Butsanddunesareactuallydyn
Usingdataisacomplexbusiness.Wellbeforeachampionship,sportsscientistsandcoachesstarttopreparetheathletebydeve
Theuniversityhasproduceda______toinformstudentsaboutthedifferentaccommodationoptionsavailable.Mealsareincluded
Choosethecorrectletter,A,BorC.WildlifeincitygardensThegroupdidextensivereadingon
Completethesentencesbelow.WriteONEWORDAND/ORANUMBERforeachanswer.The______inDrHorst’sbookareveryusefulandw
Completethenotesbelow.WriteNOMORETHANTWOWORDSforeachanswer.HistoryofweatherforecastingE
Gourdswere(introduced)towhatisnowthesouthwesternUnitedStatesby(earliest)peoples(who)migratednorth(from)Mesoame
(Inventor)ElishaGravesOtisdesignedthefirstelevator(thatitincorporated)anautomaticbrake,whichinturn(ledto)the
Thetourists’favouritevisitingplacesvaryfrompersontoperson,somewanttovisitbeautifulmountainsandrivers,othersli
随机试题
肝素的抗凝作用特点是
患儿,女,18个月,因咳喘2天人院。体检:T38℃,鼻翼煽动,三凹征(+),双肺听诊可闻及哮鸣音,余未见异常。家长述说患儿曾发生类似情况4次。初步诊断为
项目可行性研究要深化财务分析,主要内容有()。
对于钢材等大批量需要的原材料的采购,顺达公司将其通过认证的供应商组成资源市场,从中选出的供应商属于该公司的()供应商。顺达公司每年都要进行供应商的考评,某供应商2003年全年订单确认的交货总批次是12次,其中按时按量交货的实际批次是10次,则该
班集体不是自然形成的,任何一个班集体的形成都会经历组建、形成、发展的过程。()
团结协作的要点是:顾全大局,相互尊重,相互支持。( )
求函数z=3axy—x3一y3(a>0)的极值.
在数据库应用系统的需求分析阶段,设有如下工作:Ⅰ.分析与描述目标系统需要完成的功能Ⅱ.分析与描述目标系统对响应时间、存储容量的要求Ⅲ.分析与描述目标系统涉及的数据范围、数据的属性特征及数据之间的关系Ⅳ.分析与描述每项
下列关于Serv-UFTP服务器安装和配置的描述中,错误的是()。
AccordingtotheUNICEFreport,greatprogresshasbeenmadeintheprotectionofworld’schildrenfrom______.
最新回复
(
0
)