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
Opportunists and Competitors A) Growth, reproduction, and daily metabolism all require an organism to expend energy. The expendi
Opportunists and Competitors A) Growth, reproduction, and daily metabolism all require an organism to expend energy. The expendi
admin
2017-03-01
30
问题
Opportunists and Competitors
A) Growth, reproduction, and daily metabolism all require an organism to expend energy. The expenditure of energy is essentially a process of budgeting, just as finances are budgeted. If all of one’s money is spent on clothes, there may be none left to buy food or go to the movies. Similarly, a plant or animal cannot squander all its energy on growing a big body if none would be left over for reproduction, for this is the surest way to extinction.
B) All organisms, therefore, allocate energy to growth, reproduction, maintenance, and storage. No choice is involved; this allocation comes as part of the genetic package from the parents. Maintenance for a given body design of an organism is relatively constant. Storage is important, but ultimately that energy will be used for maintenance, reproduction, or growth. Therefore the principal differences in energy allocation are likely to be between growth and reproduction.
C) Almost all of an organism’s energy can be diverted to reproduction, with very little allocated to building the body. Organisms at this extreme are "opportunists". At the other extreme are "competitors", almost all of whose resources are invested in building a huge body, with a bare minimum allocated to reproduction.
D) Dandelions are good examples of opportunists. Their seed heads raised just high enough above the ground to catch the wind, the plants are no bigger than they need be, their stems are hollow, and all the rigidity comes from their water content. Thus, a minimum investment has been made in the body that becomes a platform for seed dispersal. These very short-lived plants reproduce prolifically; that is to say they provide a constant rain of seed in the neighborhood of parent plants.
E) A new plant will spring up wherever a seed falls on a suitable soil surface, but because they do not build big bodies, they cannot compete with other plants for space, water, or sunlight. These plants are termed opportunists because they rely on their seeds’ falling into settings where competing plants have been removed by natural processes, such as along an eroding riverbank, on landslips, or where a tree falls and creates a gap in the forest canopy.
F) Opportunists must constantly invade new areas to compensate for being displaced by more competitive species. Human landscapes of lawns, fields, or flowerbeds provide settings with bare soil and a lack of competitors that are perfect habitats for colonization by opportunists. Hence, many of the strongly opportunistic plants are the common weeds of fields and gardens.
G) Because each individual is short-lived, the population of an opportunist species is likely to be adversely affected by drought, bad winters, or floods. If their population is tracked through time, it will be seen to be particularly unstable—soaring and plummeting in irregular cycles.
H) The opposite of an opportunist is a competitor. These organisms tend to have big bodies, are long-lived, and spend relatively little effort each year on reproduction.
I) An oak tree is a good example of a competitor. A massive oak claims its ground for 200 years or more, out-competing all other would-be canopy trees by casting a dense shade and drawing up any free water in the soil. The leaves of an oak tree taste foul because they are rich in tannins, a chemical that renders them distasteful or indigestible to many organisms. The tannins are part of the defense mechanism that is essential to longevity.
J) Although oaks produce thousands of acorns, the investment in a crop of acorns is small compared with the energy spent on building leaves, trunk, and roots. Once an oak tree becomes established, it is likely to survive minor cycles of drought and even fire. A population of oaks is likely to be relatively stable through time, and its survival is likely to depend more on its ability to withstand the pressures of competition or predation than on its ability to take advantage of chance events.
K) It should be noted, however, that the pure opportunist or pure competitor is rare in nature, as most species fall between the extremes of a continuum, exhibiting a blend of some opportunistic and some competitive characteristics.
L) Oak wood has a density of about 0. 75 g/cm
3
, great strength and hardness, and is very resistant to insect and fungal attack because of its high tannin content. It also has very appealing grain markings, particularly when quarter-sawn.
M) Oak planking was common on high status Viking longships in the 9th and 10th centuries. The wood was hewn(砍) from green logs, by axe and wedge, to produce radial planks, similar to quarter-sawn timber. Wide, quarter-sawn boards of oak have been prized since the Middle Ages for use in interior paneling of prestigious buildings such as the debating chamber of the House of Commons in London and in the construction of fine furniture.
N) Oak wood, from Quercus robur and Quercus petraea, was used in Europe for the construction of ships until the 19th century, and was the principal timber used in the construction of European timber-framed buildings. Today oak wood is still commonly used for furniture making and flooring, timber frame buildings, and for veneer production. Barrels in which wines, sherry, and spirits such as brandy, Scotch whisky and Bourbon whiskey are aged are made from European and American oak. The use of oak in wine can add many different dimensions to wine based on the type and style of the oak. Oak barrels, which may be charred before use, contribute to the colour, taste, and aroma of the contents, imparting a desirable oaky vanillin flavour to these drinks. The great dilemma for wine producers is to choose between French and American oak woods. French oaks (Quercus robur, Quercus petraea) give the wine greater refinement and are chosen for the best wines since they increase the price compared to those aged in American oak wood. American oak contributes greater texture and resistance to ageing, but produces more violent wine bouquets. Oak wood chips are used for smoking fish, meat, cheeses and other foods.
O) Japanese oak is used in the making of professional drums from manufacturer Yamaha Drums. The higher density of oak gives the drum a brighter and louder tone compared to traditional drum materials such as maple and birch. In hill states of India, besides fuelwood and timber, the local people use oak wood for making agricultural implements. The leaves are used as fodder during lean period and bedding for livestock.
If the oak wood is quarter-sawn, there would be very obvious grain markings.
选项
答案
L
解析
句式题。根据quarter-sawn定位到L)段最后一句,原句是:It also has very appealing grain markings,particularly when quarter-sawn.这里将句式变化后,意义不变。
转载请注明原文地址:https://kaotiyun.com/show/qGU7777K
0
大学英语六级
相关试题推荐
Mostpeopleareawarethatoutdoorairpollutioncandamagetheirhealth,butmanydonotknowthatindoorairpollutionalsoca
DoctorsinBritainarewarningofanobesity(肥胖症)timebomb,whenchildrenwhoarealreadyoverweightgrowup.So,whatshouldwe
Mostpeopledon’twakeupinthemorning,combtheirhair,andwalkoutthefrontdoorandontotheworldstage.ButBritain’sP
A、ProfessorGeorge’sclassisveryinteresting.B、ProfessorJordan’sclassismoreinteresting.C、Hehasn’tattendedProfessorJ
A、Becausehecantfindanidealdate.B、Becauseheistoocommonaperson.C、BecausehehasfailedtorealizeMsdreams.D、Becau
A、TheUniversityfaculty.B、TheStudentAssociation.C、TheAlumniAssociation.D、ThePresidentoffice.C女士说组织该活动的是校友联合会,故选C。听到什么
A、Becauseitexpandsrapidlyitsretailoperations.B、Becauseitsqueezescompetitorsoutofthemarket.C、Becauseitappliesma
A、Gardeningandlandscaping.B、Retailing.C、Financing.D、Child-care.A在听到前文的gardeningandlandscaping时应竖起耳朵听其下文,接着又听到表示最高级信息的req
A、BecauseheusedtoliveinFrance.B、BecausehelikeschattingwithFrenchpeople.C、BecausehestudiesFrenchatschool.D、Be
PeoplewhospendalotoftimesurfingtheInternetaremorelikelytoshowsignsofdepression,BritishscientistssaidonWedn
随机试题
布卢姆认为最低水平的认知学习结果是知识,最高水平的认知学习结果是______。
欲速则不达所体现的心理原理是()。
A.AG增高型代谢性酸中毒 B.AG正常型代谢性酸中毒 C.代谢性碱中毒 D.呼吸性碱中毒 E.呼吸性酸中毒应用利尿剂呋塞米(速尿)时易生
A.发热伴结膜充血B.发热伴关节肿痛C.发热伴肝脾大D.发热伴咯血E.发热伴胸痛上述症状常见于下列哪种疾病
肉鸡群,35日龄,部分鸡精神萎靡,呼吸困难,心跳加快,腹部膨大,触诊有波动感剖检可见腹腔内有淡黄色透明的液体。本病的心脏主要病变是
高热、中暑的患者使用冷疗法的目的是
从事工艺、设备、产品及包装物设计,应当按照减少资源消耗和废物产生的要求,优先选择采用()、无毒无害或者低毒低害的材料和设计方案,并应当符合有关国家标准的强制性要求。
北方公司为增值税一般纳税人,增值税税率为13%,生产中所需原材料按计划成本法核算。2019年8月1日,原材料结存2000千克,计划成本为每千克50元,“材料成本差异”账户为借方余额1000元,未计提存货跌价准备。北方公司2019年8月份发生的有关原材料业务
下列对丝绸之路的描述正确的是()。
第一次明确提出“教学与科研相统一”原则的是()。
最新回复
(
0
)