首页
登录
职称英语
Lichens, probably the hardiest of all plants, live where virtually nothing e
Lichens, probably the hardiest of all plants, live where virtually nothing e
游客
2023-12-22
60
管理
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 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 are believed to supply water, minerals, and physical support to 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 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.
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 to 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. [br] It can be inferred from the passage that lichens use less energy and grow more slowly when______.
选项
A、the environment is polluted
B、they are exposed to ultraviolet rays
C、they are very old
D、the supply of water is inadequate
答案
D
解析
转载请注明原文地址:https://tihaiku.com/zcyy/3295735.html
相关试题推荐
Parentingwasneverapieceofcakeinanyage,butprobablythegreatestso
Parentingwasneverapieceofcakeinanyage,butprobablythegreatestso
[originaltext]You’veprobablyheardtheslogan"savethewhales".Doyoukn
[originaltext]You’veprobablyheardtheslogan"savethewhales".Doyoukn
[originaltext]Peoplearenoworderingandpurchasingvirtuallyanythingoverth
[originaltext]Peoplearenoworderingandpurchasingvirtuallyanythingoverth
[originaltext]You’veprobablyheardtheslogan"savethewhales".Doyoukno
[originaltext]You’veprobablyheardtheslogan"savethewhales".Doyoukno
"Water,whichisessentialforlife,costsnothing.Ontheotherhand,diamon
"Water,whichisessentialforlife,costsnothing.Ontheotherhand,diamon
随机试题
假定你是李明。最近某英文报纸开展了一个关于“如何克服学习压力和紧张情绪”的讨论,请你给报纸编辑写一封英文短信,谈谈你的建议并叙述理由。要点:(1
Charleslikedmusicverymuchwhenhewasatschool,but【B1】hewenttotheunive
Since2007,theAmericanPsychologicalAssociation(APA)hasconductedasurve
[audioFiles]2016m8x/audio_ezfj_ezflisteningd_201607_037[/audioFiles]Howto
下列关于芽孢的叙述,正确的是()。A.芽孢就是孢子 B.芽孢是细菌的生殖细
基金管理人或者基金托管人不按照规定召集基金份额持有人大会的,责令改正,可以处()
关于红细胞参考值的叙述错误的()。A.成年男性(4.0~5.5)×1012
患者男.78岁。因脑出血入院,患者大小便失禁,需加橡胶单,其上端距离床头应A.3
大班幼儿苏立对妈妈说:“妈妈,我长大了也想和你一样,做一个老师。”这是一种()
A.二氧化硅 B.二氧化碳 C.活性炭 D.三氯甲烷 E.乙醇常用的极性
最新回复
(
0
)