2020-12-21 10:53来源:互联网作者:上海管理员
摘要:托福TPO试题基本所有参加托福考生必做试题,为更好服务于广大考生,上海新航道小编会及时的更新托福TPO试题信息,包括TPO试题、答案及解析等内容。在下文中小编整理了托福TPO57阅读Passage 2原文+题目+答案解析+PDF下载,希望对大家有所帮助,如在学习过程中有问题,可以加新航道上海学校专业老师微信(微信号shnc_2018)进行咨询。
托福TPO试题基本所有参加托福考生必做试题,在下文中上海新航道托福培训小编整理了托福TPO57阅读Passage 2原文+题目+答案解析,希望对大家有所帮助!
Passage 2 The Debate over Spontaneous Generation
Until the second half of the nineteenth century, many scientists and philosophers believed that some forms of life could arise spontaneously from nonliving matter, they called this hypothetical process spontaneous generation. Not much more than 100 years ago, people commonly believed that toads, snakes, and mice could be born of moist soil, that flies could emerge from manure; and that maggots, the larvae of flies, could arise from decaying corpses.
A strong opponent of spontaneous generation, the Italian physician Francesco Redi, set out in 1668 to demonstrate that maggots did not arise spontaneously from decaying meat. Redi filled three jars with decaying meat and sealed them tightly. Then he arranged three other jars similarly but left them open. Maggots appeared in the open vessels after flies entered the jars and laid their eggs, but the sealed containers showed no signs of maggots. Still, Redi’s antagonists were not convinced, they claimed that fresh air was needed for spontaneous generation. ■So Redi set up a second experiment, in which three jars were covered with a fine net instead of being sealed.
■No larvae appeared in the net‐covered jars, even though air was present.■ Maggots appeared only when flies were allowed to leave their eggs on the meat.■
Redi’s results were a serious blow to the long‐held belief that large forms of life could arise from nonlife. However, many scientists still believed that tiny microorganisms were simple enough to be generated from nonliving materials.
The case for spontaneous generation of microorganisms seemed to be strengthened in 1745, when John Needham, an Englishman, found that even after he heated nutrient fluids (chicken broth and corn broth) before pouring them into covered flasks, the cooled solutions were soon teeming with microorganisms Needham claimed that microbes developed spontaneously from the fluids. Twenty years later, Lazzaro Spallanzani, an Italian scientist, suggested that microorganisms from the air probably had entered Needham’s solutions after they were boiled. Spallanzani showed that nutrient fluids heated after being sealed in a flask did not develop microbial growth.
Needham responded by claiming the “vital force” necessary for spontaneous generation had been destroyed by the heat and was kept out of the flasks by the seals.
This intangible “vital force” was given all the more credence shortly after Spallanzani experiment, when Laurent Lavoisier showed the importance of oxygen to life Spallanzani's observations were criticized on the grounds that there was not enough oxygen in the sealed flasks to support microbial life.
The issue was still unresolved in 1858, when the German scientist Rudolf Virchow challenged spontaneous generation with the concept of biogenesis, the claim that living cells can arise only from preexisting living cells. Arguments about spontaneous generation continued until 1861, when the work of the French scientist Louis Pasteur ended the debate.
With a series of ingenious and persuasive experiments, Pasteur demonstrated that microorganisms are present in the air and can contaminate sterile solutions, but air itself does not create microbes. He filled several short‐necked flasks with beef broth and then boiled their contents. Some were then left open and allowed to cool. In a few days, these flasks were found to be contaminated with microbes. The other flasks, sealed after boiling, were free of microorganisms. From these results, Pasteur reasoned that microbes in the air were the agents responsible for contaminating nonliving matter such as the broths in Needham’s flasks.
Pasteur next placed broth in open‐ended long‐necked flasks and bent the necks into S‐ shaped curves. The contents of these flasks were then boiled and cooled. The broth in the flasks did not decay and showed no signs of life, even after months. Pasteur’s unique design allowed air to pass into the flask, but the curved neck trapped any airborne microorganisms that might have contaminated the broth.
Pasteur showed that microorganisms can be present in nonliving matter‐‐on solids, in liquids, and in the air. His work provided evidence that microorganisms cannot originate from mysterious forces present in nonliving materials. Rather, any appearance of “spontaneous” life in nonliving solutions can be attributed to microorganisms that were already present in the air or in the fluids themselves.
相关推荐:托福TPO57阅读Passage 1原文+PDF下载
索取“原文+题目+答案+解析+MP3音频”,请加新航道上海老师微信(shnc_2018)
免费领取最新剑桥雅思、TPO、SAT真题、百人留学备考群,名师答疑,助教监督,分享最新资讯,领取独家资料。
方法1:扫码添加新航道老师
微信号:shnc_2018
方法2:留下表单信息,老师会及时与您联系
课程名称 | 班级人数 | 课时 | 学费 | 报名 |
---|---|---|---|---|
托福入门段(A段)6-10人走读班 | 6-10人 | 80课时 | ¥15800 | 在线咨询 |
托福强化段(C段)6-10人班 | 6-10人 | 96课时 | ¥30800 | 在线咨询 |
托福全程段(A+B+C段)6-10人班 | 6-10人 | 192课时 | ¥55800 | 在线咨询 |
托福特训班(4周,走读) | 8-10人 | 192 | ¥34800 | 在线咨询 |
托福特训班(6周,走读) | 8-10人 | 288 | ¥49800 | 在线咨询 |
课程名称 | 班级人数 | 课时 | 学费 | 报名 |
---|---|---|---|---|
托福精讲段(B段)20-30人班 | 20-30人 | 96课时 | ¥8800 | 在线咨询 |
托福强化段(C段)20-30人班 | 20-30人 | 96课时 | ¥7800 | 在线咨询 |
托福全程段(A+B+C段)20-30人班 | 20-30人 | 192课时 | ¥13800 | 在线咨询 |
课程名称 | 班级人数 | 课时 | 学费 | 报名 |
---|---|---|---|---|
托福入门段(A段)(6-10人,住宿) | 6-10人 | 80课时 | ¥17800 | 在线咨询 |
托福强化段(C段)6-10人班住宿 | 152课时 | ¥33800 | 在线咨询 | |
托福全程班(A+B+C段)6-10人班住宿 | 6-10人 | 304课时 | ¥60800 | 在线咨询 |
托福长线班(6-10人,住宿) | 6-10人 | 272课时 | ¥77800 | 在线咨询 |
托福词汇语法住宿班(A段)(6-10人) | 6-10人 | 48课时 | ¥8800 | 在线咨询 |
课程名称 | 班级人数 | 课时 | 学费 | 报名 |
---|---|---|---|---|
托福全程段(A+B+C段)20-30人班住宿 | 20-30人 | 192课时 | ¥15800 | 在线咨询 |
托福强化段(C段)20-30人班住宿 | 20-30人 | 96课时 | ¥8800 | 在线咨询 |
托福精讲段(B段)20-30人班住宿 | 20-30人 | 96课时 | ¥9800 | 在线咨询 |
课程名称 | 班级人数 | 课时 | 学费 | 报名 |
---|---|---|---|---|
托福一对一 | 1 | 按需定制 | ¥980元 | 在线咨询 |
托福免费试听课 | ¥0元 | 在线咨询 |
课程名称 | 班级人数 | 课时 | 学费 | 报名 |
---|---|---|---|---|
小托福课程 | 6人 | 54小时 | ¥20800 | 在线咨询 |
小托福考试技巧进阶课程 | 30 | ¥9800 | 在线咨询 |
免责声明
1、如转载本网原创文章,请表明出处;
2、本网转载媒体稿件旨在传播更多有益信息,并不代表同意该观点,本网不承担稿件侵权行为的连带责任;
3、如本网转载稿、资料分享涉及版权等问题,请作者见稿后速与新航道联系(电话:021-64380066),我们会第一时间删除。
地址:徐汇区文定路209号宝地文定商务中心1楼
乘车路线:地铁1/4号线上海体育馆、3/9号线宜山路站、11号线上海游泳馆站
总部地址:北京市海淀区中关村大街28-1号6层601 集团客服电话:400-097-9266 总部:北京新航道教育文化发展有限责任公司
Copyright © www.xhd.cn All Rights Reserved 京ICP备05069206