已阅读5页,还剩9页未读, 继续免费阅读
版权说明:本文档由用户提供并上传,收益归属内容提供方,若内容存在侵权,请进行举报或认领
文档简介
智课网TOEFL备考资料文勇黄金阅读最新版:生物钟 摘要: 刘文勇新托福黄金阅读最新版文本及答案,高清PDF格式支持免费下载,一共71篇,包括原刘文勇黄金阅读29篇,下面是文勇黄金阅读最新版:生物钟,希望对大家备考托福阅读考试有所帮助。 文勇黄金阅读最新版:Biological Clocks 生物钟 Survival and successful reproduction usually require the activities of animals to be coordinated with predictable events around them. Consequently, the timing and rhythms of biological functions must closely match periodic events like the solar day, the tides, the lunar cycle, and the seasons. The relations between animal activity and these periods, particularly for the daily rhythms, have been of such interest and importance that a huge amount of work has been done on them and the special research field of chronobiology has emerged. Normally, the constantly changing levels of an animals activitysleeping, feeding, moving, reproducing, metabolizing, and producing enzymes and hormones, for exampleare well coordinated with environmental rhythms, but the key question is whether the animals schedule is driven by external cues, such as sunrise or sunset, or is instead dependent somehow on internal timers that themselves generate the observed biological rhythms. Almost universally, biologists accept the idea that all eukaryotes (a category that includes most organisms except bacteria and certain algae) have internal clocks. By isolating organisms completely from external periodic cues, biologists learned that organisms have internal clocks. For instance, apparently normal daily periods of biological activity were maintained for about a week by the fungus Neurospora when it was intentionally isolated from all geophysical timing cues while orbiting in a space shuttle. The continuation of biological rhythms in an organism without external cues attests to its having an internal clock. When crayfish are kept continuously in the dark, even for four to five months, their compound eyes continue to adjust on a daily schedule for daytime and nighttime vision. Horseshoe crabs kept in the dark continuously for a year were found to maintain a persistent rhythm of brain activity that similarly adapts their eyes on a daily schedule for bright or for weak light. Like almost all daily cycles of animals deprived of environmental cues, those measured for the horseshoe crabs in these conditions were not exactly 24 hours. Such a rhythm whose period is approximatelybut not exactlya day is called circadian. For different individual horseshoe crabs, the circadian period ranged from 22.2 to 25.5 hours. A particular animal typically maintains its own characteristic cycle duration with great precision for many days. Indeed, stability of the biological clocks period is one of its major features, even when the organisms environment is subjected to considerable changes in factors, such as temperature, that would be expected to affect biological activity strongly. Further evidence for persistent internal rhythms appears when the usual external cycles are shiftedeither experimentally or by rapid east-west travel over great distances. Typically, the animals daily internally generated cycle of activity continues without change. As a result, its activities are shifted relative to the external cycle of the new environment. The disorienting effects of this mismatch between external time cues and internal schedules may persist, like our jet lag, for several days or weeks until certain cues such as the daylight/darkness cycle reset the organisms clock to synchronize with the daily rhythm of the new environment. Animals need natural periodic signals like sunrise to maintain a cycle whose period is precisely 24 hours. Such an external cue not only coordinates an animals daily rhythms with particular features of the local solar day but alsobecause it normally does so day after day-seems to keep the internal clocks period close to that of Earths rotation. Yet despite this synchronization of the period of the internal cycle, the animals timer itself continues to have its own genetically built-in period close to, but different from, 24 hours. Without the external cue, the difference accumulates and so the internally regulated activities of the biological day drift continuously, like the tides, in relation to the solar day. This drift has been studied extensively in many animals and in biological activities ranging from the hatching of fruit fly eggs to wheel running by squirrels. Light has a predominating influence in setting the clock. Even a fifteen-minute burst of light in otherwise sustained darkness can reset an animals circadian rhythm. Normally, internal rhythms are kept in step by regular environmental cycles. For instance, if a homing pigeon is to navigate with its Sun compass, its clock must be properly set by cues provided by the daylight/darkness cycle. Paragraph 1:Survival and successful reproduction usually require the activities of animals to be coordinated with predictable events around them. Consequently, the timing and rhythms of biological functions must closely match periodic events like the solar day, the tides, the lunar cycle, and the seasons. The relations between animal activity and these periods, particularly for the daily rhythms, have been of such interest and importance that a huge amount of work has been done on them and the special research field of chronobiology has emerged. Normally, the constantly changing levels of an animals activitysleeping, feeding, moving, reproducing, metabolizing, and producing enzymes and hormones, for exampleare well coordinated with environmental rhythms, but the key question is whether the animals schedule is driven by external cues, such as sunrise or sunset, or is instead dependent somehow on internal timers that themselves generate the observed biological rhythms. Almost universally, biologists accept the idea that all eukaryotes (a category that includes most organisms except bacteria and certain algae) have internal clocks. By isolating organisms completely from external periodic cues, biologists learned that organisms have internal clocks. For instance, apparently normal daily periods of biological activity were maintained for about a week by the fungus Neurospora when it was intentionally isolated from all geophysical timing cues while orbiting in a space shuttle. The continuation of biological rhythms in an organism without external cues attests to its having an internal clock. 1. The word Consequently in the passage is closest in meaning to Therefore Additionally Nevertheless Moreover 2. In paragraph 1, the experiment on the fungus Neurospora is mentioned to illustrate the existence of weekly periods of activity as well as daily ones the finding of evidence that organisms have internal clocks the effect of space on the internal clocks of organisms the isolation of one part of an organisms cycle for study 3. According to paragraph 1, all the following are generally assumed to be true EXCEPT: It is important for animals daily activities to be coordinated with recurring events in their environment. Eukaryotes have internal clocks. The relationship between biological function and environmental cycles is a topic of intense research. Animals daily rhythms are more dependent on external cues than on internal clocks. Paragraph 2:When crayfish are kept continuously in the dark, even for four to five months, their compound eyes continue to adjust on a daily schedule for daytime and nighttime vision. Horseshoe crabs kept in the dark continuously for a year were found to maintain a persistent rhythm of brain activity that similarly adapts their eyes on a daily schedule for bright or for weak light. Like almost all daily cycles of animals deprived of environmental cues, those measured for the horseshoe crabs in these conditions were not exactly 24 hours. Such a rhythm whose period is approximatelybut not exactlya day is called circadian. For different individual horseshoe crabs, the circadian period ranged from 22.2 to 25.5 hours. A particular animal typically maintains its own characteristic cycle duration with great precision for many days. Indeed, stability of the biological clocks period is one of its major features, even when the organisms environment is subjected to considerable changes in factors, such as temperature, that would be expected to affect biological activity strongly. Further evidence for persistent internal rhythms appears when the usual external cycles are shiftedeither experimentally or by rapid east-west travel over great distances. Typically, the animals daily internally generated cycle of activity continues without change. As a result, its activities are shifted relative to the external cycle of the new environment. The disorienting effects of this mismatch between external time cues and internal schedules may persist, like our jet lag, for several days or weeks until certain cues such as the daylight/darkness cycle reset the organisms clock to synchronize with the daily rhythm of the new environment. 4. The word persistent in the passage is closest in meaning to adjusted strong enduring predicted 5. Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information. Stability, a feature of the biological clocks period, depends on changeable factors such as temperature. A major feature of the biological clock is that its period does not change despite significant changes in the environment. A factor such as temperature is an important feature in the establishment of the biological clocks period. Biological activity is not strongly affected by changes in temperature. 6. According to paragraph 2, which of the following is true about the circadian periods of animals deprived of environmental cues? They have the same length as the daily activity cycles of animals that are not deprived of such cues. They can vary significantly from day to day. They are not the same for all members of a single species. They become longer over time. 7. According to paragraph 2, what will an animal experience when its internal rhythms no longer correspond with the daily cycle of the environment? Disorientation Change in period of the internal rhythms Reversal of day and night activities Increased Sensitivity to environmental factors 8. In paragraph 2, the author provides evidence for the role of biological clocks by listing the daily activities of an animals cycle: sleeping, feeding, moving, reproducing, metabolizing, and producing enzymes and hormones describing the process of establishing the period of a biological clock presenting cases in which an animals daily schedule remained stable despite lack of environmental cues contrasting animals whose daily schedules fluctuate with those of animals whose schedules are constant 9. The word duration in the passage is closest in meaning to length feature process repetition 10. In paragraph 2, why does the author mention that the period for different horseshoe crabs ranges from 22.2 to 25.5 hours? To illustrate that an animals internal clock seldom has a 24-hour cycle To argue that different horseshoe crabs will shift from daytime to nighttime vision at different times To illustrate the approximate range of the circadian rhythm of all animals To support the idea that external cues are the only factors affecting an animals periodic behavior Paragraph 3:Animals need natural periodic signals like sunrise to maintain a cycle whose period is precisely 24 hours. Such an external cue not only coordinates an animals daily rhythms with particular features of the local solar day but alsobecause it normally does so day after day-seems to keep the internal clocks period close to that of Earths rotation. Yet despite this synchronization of the period of the internal cycle, the animals timer itself continues to have its own genetically built-in period close to, but different from, 24 hours. Without the external cue, the difference accumulates and so the internally regulated activities of the biological day drift continuously, like the tides, in relation to the solar day. This drift has been studied extensively in many animals and in biological activities ranging from the hatching of fruit fly eggs to wheel running by squirrels. Light has a predominating influence in setting the clock. Even a fifteen-minute burst of light in otherwise sustained darkness can reset an animals circadian rhythm. Normally, internal rhythms are kept in step by regular environmental cycles. For instance, if a homing pigeon is to navigate with its Sun compass, its clock must be properly set by cues provided by the daylight/darkness cycle. 11. The word it in the passage refers to an external cue such as sunrise the daily rhythm of an animal the local solar day a cycle whose period is precisely 24 hours 12. The word sustained in the passage is closest in meaning to intense uninterrupted natural periodic Paragraph 3:Animals need natural periodic signals like sunrise to maintain a cycle whose period is precisely 24 hours. Such an external cue not only coordinates an animals daily rhythms with particular features of the local solar day but alsobecause it normally does so day after day-seems to keep the internal clocks period close to that of Earths rotation. Yet despite this synchronization of the period of the internal cycle, the animals timer itself continues to have its own genetically built-in period close to, but different from, 24 hours. Without the external cue, the difference accumulates and so the internally regulated activities of the biological day drift continuously, like the tides, in relation to the solar day. This drift has been studied extensively in many animals and in biological activities ranging from the hatching of fruit fly eggs to wheel running by squirrels. Light has a predominating influence in setting the clock. Even a fifteen-minute burst of light in otherwise sustained darkness can reset an animals circadian rhythm. Normally, internal rhythms are kept in step by regular environmental cycles. For instance, if a homing pigeon is to navigate with its Sun compass, its clock must be properly set by cues provided by the daylight/darkness cycle. 13. Look at the four squares that indicate where the following sentence could be added to the passage. Because the internal signals that regulate waking and going to sleep tend to align themselves with these external cues, the external clock appears to dominate the internal clock. Where would the sentence best fit? 14. Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points. The activity of animals is usually coordinated with periodically recurring events in the environment. Answer Choices Most animals survive and reproduce successfully without coordinating their activities to external environmental rhythms. The circadian period of an animals internal clock is genetically determined and basically unchangeable. Environmental cues such as a change in temperature are enough to reset an animals clock. Animals have internal clocks that influence their activities even when environmental cues are absent. Animals are less affected by large differences between their internal rhythms and the local solar day than are humans Because an animals internal clock does no
温馨提示
- 1. 本站所有资源如无特殊说明,都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
- 2. 本站的文档不包含任何第三方提供的附件图纸等,如果需要附件,请联系上传者。文件的所有权益归上传用户所有。
- 3. 本站RAR压缩包中若带图纸,网页内容里面会有图纸预览,若没有图纸预览就没有图纸。
- 4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
- 5. 人人文库网仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对用户上传分享的文档内容本身不做任何修改或编辑,并不能对任何下载内容负责。
- 6. 下载文件中如有侵权或不适当内容,请与我们联系,我们立即纠正。
- 7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
最新文档
- 人教A版安徽省合肥市普通高中联盟2023-2024学年高二上学期1月期末联考数学试题
- 武术说课稿课件
- 基层 工会 课件
- 介绍鲁滨逊课件
- 高考地理一轮复习第六章自然环境的整体性和差异性第一节植被与土壤课件
- 西京学院《微机原理与接口技术》2021-2022学年期末试卷
- 学管师工作核心说课
- 西京学院《教师语言艺术》2022-2023学年第一学期期末试卷
- 西京学院《电机控制技术》2021-2022学年期末试卷
- 学会读书 课件
- 2024年山东省东营市中考语文试题含解析
- 天然气管网安装工程施工过程岗位操作指南
- 2024年招商引资居间合同
- 船用甲板刷商业机会挖掘与战略布局策略研究报告
- 公司网络安全制度
- 跨学科主题学习- 探索外来食料作物传播史(课件)七年级地理上册同步高效备课课件(人教版2024)
- 学校编制外临时代课教师聘用管理办法
- 第五单元测试卷(单元测试)-2024-2025学年统编版六年级上册语文
- 五级应急救援员职业鉴定考试题库(含答案)
- 第7课 实践出真知-【中职专用】2024年中职思想政治《哲学与人生》金牌课件(高教版2023·基础模块)
- 《电工电子技术基础》高职全套教学课件
评论
0/150
提交评论