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
A reconstruction of an ancient tree from one of Earth’s first forests reveals that the plants were topped with fronds(蕨类植树物的叶子)
A reconstruction of an ancient tree from one of Earth’s first forests reveals that the plants were topped with fronds(蕨类植树物的叶子)
admin
2009-04-23
30
问题
A reconstruction of an ancient tree from one of Earth’s first forests reveals that the plants were topped with fronds(蕨类植树物的叶子) and not leaves. The crown(树冠) of an ancient tree found in a place from which stone is dug out in New York has shed light on the look of the world’s earliest forests believed to have thrived about 390 million years ago.
The discovery of this 390-million yes, old, six-foot upper portion of an ancient tree trunk allowed scientists to create a composite picture of the entire plant when they put it together with fragments of a trunk found in the same site a year before and with tree stumps recovered more than 130 years ago. The remains have been widely reported as "evidence of the Earth’s oldest forest," according to a paper published in this week’s Nature.
"The basic point of this paper is two things," says lead author William Stein. "We now have clear evidence what these stumps really were", and we also have "real strong evidence of the structure of these forms."
From the fossil reconstruction, the team of scientists determined that a tree comprising all these parts could grow about 30 feet tall. According to Stein, the base would have been massive— on the order of 2.5 feet in diameter—and a large, single trunk with vertical ridges, topped by a leafless crown of a material resembling fronds on ferns(蕨类) and palms.
By piecing together the fragments, the team was able to get an idea of what forest might have looked like 390 million years ago. Stein estimates these trees would have been "fairly closely spaced," about 3 to 16 feet apart, and that they would have dropped a load of fronds from their branches onto the forest floor. Amongst these trees were likely smaller plants and shrubs. These trees likely let more sunlight through than modern-day counterparts, for their branch structures did not fan out as far, forming an umbrella-like shape.
Stein notes that the rise of forests with trees like these caused the removal of CO2 from the air and temperatures to drop, creating climates like those experienced today. The drop CO2 in levels, he says, likely led to the evolution of flat leaves on trees to attract and retain more of the gas, which plants need. Up next, he says: research will focus on "the internal structure of the plants to work out how they grew" as well as "how they functioned physiologically, particularly the relationship with CO2."
选项
A、It helps people know that ancient trees have no trunk.
B、It provides us new information about the appearance of the earliest forest.
C、It provides evidence for the existence of trees 397 million years ago.
D、It provides evidence for the bloom of trees 397 million years ago.
答案
B
解析
根据题干中the crown of an ancient tree found in New York,可以定位到第一段的最后一句话。该句提到一个古树树冠在纽约的一个采石的地方被发现,这为了解三亿九百万年前世界早期森林的样子提供了新的信息。文章没有提到这个古树树冠的出土使人们知道古树没有树干,故可排除A;三亿九百万年前有树木这一事实也不是以这个古树树冠的出土为证据的,故排除C;人们所认为三亿九百万年前树木很茂盛,但这个古树树冠的出土并未证明这一点,故可排除D。
转载请注明原文地址:https://jikaoti.com/ti/bl7MFFFM
0
大学英语六级
相关试题推荐
Ifyouwanttobelikedininterviews,youneedtobeconfident.Butatthesametime,youshouldalsobehonest.Thereisasim
A、Inanairport.B、Inaplane.C、Inahotel.D、Inastreet.A根据女士所说it’sthefinalcallforflight56910可知,现在在播放最后一遍56910航班的登机广播,
______thegreatdifferencesbetweenthem,theyfellinlovewitheachotheratfirstsight.
Theyare______studentsthattheyallperformedwellinthefinalexaminations.
IntheUnitedStatesandCanada,aprom,shortforpromenade,isaformaldance,orgettingtogetherofhighschoolstudents.It
WantedxxxForeignLanguageInstituteisaforeignlanguagestudyinginstitute.NowweareseekingfortwoEnglishteachers.
Whatisthepassagetalkingabout?______.
Thehumanbraincontains10thousandmillioncellsandeachofthesemayhaveathousandconnections.Suchenormousnumbersused
A、Atabank.B、Atarailwaystation.C、Atanairport.D、Ataparkinglot.C本题考查的是地点方位。通过关键词Flight(班机)CAl02再加上词语finalcall(最后通告)和
A、Hesuggeststhewomanbuyanewbicycle.B、Hesuggestslendinghisownbicycletothewoman.C、Hesuggeststhewomanhaveher
随机试题
福建省有“世界宗教博物馆”之称的城市是()。
砚(inkslab)同笔、墨、纸一起记录着中国古老的历史和悠久的文化。砚的材质和样式丰富多彩,是文房四宝中流传至今数量最多的。砚的制作融合了中国传统雕刻、绘画和文学因素,凝结了众多制砚匠人的智慧。砚的历史十分悠久,最初与研磨棒(grindingstic
大客车通过险桥、漫水桥、渡口、危险地段前,要做什么以保证安全?
设关系模式R和S具有相同的结构,则{tItER∧t∈S}与关系代数表达式________等价。
病人的首选治疗是
A.维生素B1B.维生素AC.维生素CD.维生素EE.维生素P鱼鳞病是缺乏
组成中不含人参、大枣、甘草的方剂是
最有利于提高财务资源利用效率的财务管理体制是()。
葡聚糖是现在人气极高,食品科学和工业界很看好的一种可溶性纤维。某些葡聚糖也似乎对于增强免疫力更有效果——但是任何的膳食纤维都会对健康大有裨益。与其花大钱去买“特别的”“增强免疫力”的纤维,多吃一些经济实惠的富含膳食纤维的食物是不是更划算?根据上文推断,作者
1/3,1/3,4/9,2/3,16/15,()
最新回复
(
0
)