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
Orchids are unique in having the most highly developed of all blossoms, in which the usual male and female reproductive organs a
Orchids are unique in having the most highly developed of all blossoms, in which the usual male and female reproductive organs a
admin
2010-07-06
43
问题
Orchids are unique in having the most highly developed of all blossoms, in which the usual male and female reproductive organs are fused in a single structure called the column. The column is designed so that a single pollination will fertilize hundreds of thousands, and in some cases millions, of seeds, so microscopic and light that they are easily carried by the breeze. Surrounding the column are three sepals and three petals, sometimes easily recognizable as such, often distorted into gorgeous, weird, but always functional shapes. The most noticeable of the petals is called the labellum, or lip. It is often dramatically marked as an unmistakable landing strip to attract the specific insect the orchid has chosen as its pollinator.
To lure their pollinators from afar, orchids use appropriately intriguing shapes, colors, and scents. At least 50 different aromatic compounds have been analyzed in the orchid family, each blended to attract one, or at most a few, species of insects or birds. Some orchids even change their scents to interest different insects at different times.
Once the right insect has been attracted, some orchids present all sorts of one-way obstacle courses to make sure it does not leave until pollen has been accurately placed or removed. By such ingenious adaptations to specific pollinators, orchids have avoided the hazards of rampant crossbreeding in the wild, assuring the survival of species as discrete identities. At the same time they have made themselves irresistible to collectors.
Which of the following is NOT mentioned as a means by which an orchid attracts insects?
选项
A、Size.
B、Shape.
C、Color.
D、Scent.
答案
A
解析
转载请注明原文地址:https://www.kaotiyun.com/show/BBDd777K
本试题收录于:
公共英语四级笔试题库公共英语(PETS)分类
0
公共英语四级笔试
公共英语(PETS)
相关试题推荐
Fordecades,postersdepictingrabbitswithinflamed,reddenedeyessymbolizedcampaignsagainstthetestingofcosmeticsonani
Fordecades,postersdepictingrabbitswithinflamed,reddenedeyessymbolizedcampaignsagainstthetestingofcosmeticsonani
Fordecades,postersdepictingrabbitswithinflamed,reddenedeyessymbolizedcampaignsagainstthetestingofcosmeticsonani
YouwillhearaninterviewwithProf.JesseAusubelabouthisoptimisticattitudestowardsenvironmentalissuestoday.Asyouli
YouwillhearaninterviewwithProf.JesseAusubelabouthisoptimisticattitudestowardsenvironmentalissuestoday.Asyouli
Agingbabyboomersaredeterminedtofighttheagingprocess.Theyspendmillionsofdollarsayearon【C1】______theyperceiveas
Between1852,when【C1】______wasfirstestablishedthatMountEverestwasthehighestmountainonearth,and1953,whenEdmundHi
Between1852,when【C1】______wasfirstestablishedthatMountEverestwasthehighestmountainonearth,and1953,whenEdmundHi
Throughouthistorytherehavebeenmanyunusualtaxesleviedonsuchthingsashats,Beds,Baths,marriages,andfunerals.Aton
A=HydropowerB=NuclearpowerC=SolarpowerD=WindpowerWhichpower(power’s)...wasdevelopedtoprovideelectricity
随机试题
确定加工余量大小的方法有________、________和________三种方法。
装配工艺规程的内容包括()。
长期应用某种药物后需要增加剂量才能奏效,这种作用为()
应激反应
刘某,多次实施抢劫行为,手段恶劣且数额较大,后来在一次抢劫活动中被警察当场抓获。由于该案是被公安人员当场发现,而且事实清楚,因而在本案的诉讼程序中:()
1.背景材料:某沥青混凝土路面工程,路面结构形式自上而下依次为:上面层4cmAC-16(I)中粒式沥青混凝土、中面层6cm.AC-25(I)粗粒式沥青混凝土,下面层8cmAC-25(I)粗粒式沥青混凝土,工程量为:上面层482200m2、
中国台湾证券交易所目前发布的股价指数中,最有代表性的是()。
下列变量中,不属于确定市场细分变量的是()
下列关于商业银行管理和使用理财资金的说法,正确的有()。
F
最新回复
(
0
)