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
2025-01-13
33
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/3910295.html
相关试题推荐
[originaltext]Peoplearenoworderingandpurchasingvirtuallyanythingoverth
[originaltext]Peoplearenoworderingandpurchasingvirtuallyanythingoverth
[originaltext]You’veprobablyheardtheslogan"savethewhales".Doyoukno
[originaltext]You’veprobablyheardtheslogan"savethewhales".Doyoukno
"Water,whichisessentialforlife,costsnothing.Ontheotherhand,diamon
"Water,whichisessentialforlife,costsnothing.Ontheotherhand,diamon
"Water,whichisessentialforlife,costsnothing.Ontheotherhand,diamon
Howwelookandhowweappeartoothersprobablyworriesusmorewhenarein
Howwelookandhowweappeartoothersprobablyworriesusmorewhenarein
Mostgrowingplantscontainmuchmorewaterthanallothermaterialscombined
随机试题
[originaltext]M:I’vespentallthemoneythismonth.That’sterrible.W:Yous
Sleepispartofaperson’sdailyactivitycycle.Thereareseveraldiffere
关于正常阴道脱落细胞涂片像的各项中,哪一项是正确的A.角化系数受孕激素影响而升高
新闻评论强烈的新闻性既体现在强烈的时效性,又体现在()。A.现实的针对性 B
力系合力等于零是平面汇交力系平衡的()。A.充分条件 B.必要条件 C.充
下列关于投资方案资本金的说法错误的是()。A:投资方案资本金是在投资方案总投资
脂质体的包封率不得低于()。A:50% B:60% C:70% D:80
砌体结构房屋,二层某外墙立面如下图所示,墙内构造柱的设置符合《建筑抗震设计规范》
县级以上地方各级预算的调整方案应当提请本级人民代表大会审查和批准。()
关于境外投资项目管理的说法,正确的是()。A.境外投资项目实行核准的范围包
最新回复
(
0
)