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
It was a sorry end. Cut down in his prime, the cunning thief lay on the slab, his cold body offering pathologist Brett Gartrell
It was a sorry end. Cut down in his prime, the cunning thief lay on the slab, his cold body offering pathologist Brett Gartrell
admin
2009-06-24
19
问题
It was a sorry end. Cut down in his prime, the cunning thief lay on the slab, his cold body offering pathologist Brett Gartrell no outward sign of how he. had met his maker. Once Gartrell had wielded his scalpel, however, the cause became, clear: a belly stuffed with sticky brown gunk. Diagnosis? Death by chocolate.
66.______
If you’re reading this after scoffing your fifteenth chocolate Santa, don’t panic: We humans have been safely enjoying the beans of the cacao plant, Theobroma cacao, for millennia. Theobroma is Greek for "food of the gods", reflecting the Mayan belief that cocoa had divine origins. Every April, they sacrificed a dog with cacao-coloured markings in honour of Ek Chuah, the god of cacao.
67.______
It was methylxanthines that did for the kea too. Gartrell, a wildlife pathologist at Massey University in Palmerston North, New Zealand, is wearily familiar with keas’ propensity m poison themselves. Besides being arguably the world’s smartest birds, keas are extraordinarily inquisitive foragers, using their beaks to rip open tents and backpacks, open garbage bins and even pry pieces off cars in their quest for food. "They’ll try anything that is vaguely edible, which is part of the reason they get into trouble", says Gartrell.
68.______
The reason humans don’t turn up their toes after bingeing on chocolate is largely down to the speed at which our bodies metabolise theobromine, the most abundant methylxanthine in chocolate. Rats metabolise it much more slowly than humans, and dogs are slower still. There are no reliable figures for theobromine toxicity in humans, but based on caffeine toxicity an average adult would have to gorge on around 50 kilograms of milk chocolate in a single sitting to get anywhere near a lethal dose.
69.______
Coyotes are a serious pest in the U.S., killing $44 million worth of livestock each year, damaging property and attacking people and pets. Measures such as fences are often ineffective. Sometimes culling them is the only option but unfortunately the poisons now used, such as sodium cyanide, are toxic to humans and most other animals too. "If we can come up with something that is more selective, it offers an advantage", says Johnston. "It’s a more responsible approach".
70.______
Methylxanthines are also shaping up as a way to dispatch other pests. Earl Campbell of the U.S. Pacific Basin Agricultural Research Center in Hilo, Hawaii, discovered that caffeine sprays could kill two species of noisy and ecologically damaging Caribbean tree frogs that have plagued the island since they were accidentally introduced in the 1980s. Campbell noticed that the spray also killed slugs. His colleague Robert Hollingsworth then found that caffeine spray made snails kick the bucket too. Hollingsworth is now developing caffeine as an alternative to conventional pesticides, such as those used in slug pellets. "There’s a huge amount of interest in using botanical extracts", he says. "People are more comfortable with things that are natural".
A. Knife-wielding priests aside, chocolate is still bad news for many animals. Cocoa beans are naturally rich in caffeine and its chemical relatives theobromine and theophylline, collectively called methylxanthines. To humans these are little more than benign stimulants, but to a number of animals they are highly toxic. Just 240 grams of unsweetened dark chocolate contains enough methylxanthines to kill a 40-kilogram dog, about the size of a German shepherd.
B. The methylxanthines are just a start. "Cocoa is a real gold.mine of different components", says Herwig Bernaert, research manager at Barry Callebaut, a chocolate manufacturer in Zurich, Switzerland. Cocoa contains more than 700 compounds and there is a great deal of research on which of these can affect people or other creatures.
C. Methylxanthines looked as though they might fit the bill. After testing the toxicity of several different types of chocolate, Johnson came up with a mixture of theobromine and caffeine that killed coyotes quickly and with minimal distress. The mixture can be hidden in bait and is currently undergoing field tests.
D. The observation that methylxanthines are highly toxic to animals, with dogs being especially vulnerable, prompted John Johnston, a chemist at the U.S. Department of Agriculture in Fort Collins, Colorado, to investigate chocolate as a more selective way of controlling coyotes.
E. Divine—yes. Delicious—absolutely. But deadly? For some it certainly is. The corpse on Gartrell’s slab belonged not to a human but to a kea, an endangered New Zealand parrot. Like many animals, keas are acutely sensitive to chemicals in chocolate that are harmless to humans in all but huge doses. Scientists are now studying these chemicals, along with other substances in cocoa, hoping to exploit their toxic effects to control pests or microbes.
F. The dead kea was found outside a hotel kitchen in the holiday resort of Mount Cook Village in the Southern Alps. It had eaten more than 20 grams of dark chocolate, presumably pilfered from the kitchen garbage. "He’d really pigged out", says Gartrell. The ill-fated kea was by no means alone in its folly. Veterinary journals are peppered with stories of dogs, cats, parrots, foxes, badgers and other animals dropping dead after finding chocolate or being fed it by well- meaning humans.
选项
答案
D
解析
转载请注明原文地址:https://kaotiyun.com/show/2zTd777K
本试题收录于:
公共英语五级笔试题库公共英语(PETS)分类
0
公共英语五级笔试
公共英语(PETS)
相关试题推荐
FinancingCollegeTrainingHighschoolstudentswho,aftergraduation,wouldliketocontinuetheireducationarefrequently
FinancingCollegeTrainingHighschoolstudentswho,aftergraduation,wouldliketocontinuetheireducationarefrequently
A.Necessityfordevelopingadulteducation.B.Earlydaysofadulteducation.C.Waysofreceivingadulteducation.D.Growtho
TheEnglishWeather"Othercountrieshaveaclimate;inEnglandwehaveweather".Thisstatement,oftenmadebyEnglishmentode
Accordingtotheauthor,whichofthefollowingstatementsistrue?Peleiscitedasanexampleinthesecondparagraphtoillu
AThirstyWorldTheworldisnotonlyhungry;itisalsothirstyforwater.Thisseemsstrangetoyou,sincenearly75%ofth
ATheOrganizationofAnArticleBCheckYourReadingSpeedCAWaytoIncreaseYourReadingSpeedDCheckYourUnderstandin
TheInternetHouseAleadingBritishbuildinganddesigncompanyhasjustannouncedtheirplansforthehomeofthefuture.T
Herfatherwasaquietmanwithgracefulmanners.
随机试题
Howarabbitstudyandanex-studentboostmyhopesforafutureof‘loveanddignity’A)Atwhatevergradelevelteachersfind
近年来,很多地方实施了院士引进计划,并针对院士建立了容错机制,让其潜心研发而无后顾之忧。有学者对此指出,容错机制、宽松的考核评价机制是每个科研工作者梦寐以求的理想科研环境,应该提供给本身正处于创新能力高峰期的青年科学家,而不是已取得较高学术成就的院士。
ThequestionofhowAmericansspentand,crucially,savedmoneyoverthepasttwoyearsloomslargeovertheeconomytoday.Ins
结构上不含杂环的镇痛药是()
患者,女性,51岁,农民。因“阵发性胸闷、心悸12小时,伴晕厥1次”入院。患者于入院前12小时清晨起床蹲位排便后起立行走时突发胸闷、心悸、黑嚎,呼之不应,持续约10分钟,由急救车急诊入院。既往身体健康。查体:神志清,心肺未发现异常体征。拟诊“冠心病,心绞痛
当事人提出证据证明仲裁裁决有,下列哪些情形的,可以向仲裁委员会所在地的中级人民法院申请撤销裁决?()
教学是对学生进行德育工作最基本、最经常和最有效的途径。()
下列说法正确的是()。
设z=f(x,y)在点O(0,0)的某邻域内有定义,向量e+=i,e-=-i,与表示相应的方向导数,则与都存在是存在的()
Acenturyago,theimmigrantsfromacrosstheAtlanticincludedsettlersandsojourners.Alongwiththemanyfolkslookingtoma
最新回复
(
0
)