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TPO59阅读Passage 2完整原文,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TPO59阅读Passage 2完整原文,希望对大家有所帮助!
托福TPO59阅读Passage 2完整原文
Dealing with Extreme Cold
There are a number of environments in which organisms are exposed to temperatures below 0°C and thus the risk of freezing. In polar regions, terrestrial organisms are exposed to freezing temperatures for most of the year. In more temperate regions, they may have to tolerate several months of winter, when subzero temperatures persist for long periods of time. High mountains are another place where there is permanent snow and ice, even at the equator. Exposure to subzero temperatures may occur on a daily and/or seasonal basis.
Endothermic animals (warm-blooded animals) can stop their bodies from freezing by generating their own heat. They retain heat because of the insulation provided by feathers or fur, and the layer of fat beneath the skin. Other heat conservation measures include huddling together, recovering heat from exhaled breath, and recovering heat from the extremities of the body. Endotherms can remain active in the cold if they can find enough food, or they can reduce their metabolism and lie dormant until warmer conditions return. Although air temperatures may be low, the temperature beneath an insulating layer of snow, under the ground, or at the bottom of a lake may remain above 0°C. Most organisms, however, can neither generate their own heat nor avoid the freezing temperatures, and for them, the choice is to survive ice formation within their bodies or to prevent their bodies from freezing.
Organisms run the risk of freezing at temperatures that are below the melting point of their body and cell fluids. There are two main responses: either they can survive ice forming within them (they are freezing tolerant) or they have mechanisms that ensure that their flu ids remain liquid at temperatures that are below the freezing point of water and the melting point of their body fluids (they are freeze avoiding). The strategy that an organism uses depends on the freeze This may cause its body fluids to freeze by the ice traveling across the cell or body wall, or through body openings-a process known as inoculative freezing. Most organisms surviving low temperatures in such environments are thus likely to be freezing tolerant, since inoculative freezing will cause their bodies to freeze Some, however, may have a structure such as a cuticle, eggshell, cocoon, or sheath that allows them to prevent inoculative freezing by acting as a barrier to the spread of ice into their bodies This allows them to maintain their body or cell fluids as liquids, despite the fact that their surfaces are in contact with external ice, and enables them to avoid inoculative freezing. In a situation where the organism is likely to be exposed to subzero temperatures with little or no water in contact with its surface (many terrestrial insects, for example), it does not have the problem of inoculative freezing and it is perhaps easier for it to maintain its body fluids in a liquid state at low temperatures and thus survive by avoiding freezing. structure and physiology it has developed during its evolutionary history and on the particular demands of its environment. If the organism is living in a wet or damp environment, ice is likely to make contact with its surface when its surroundings
The two strategies of cold survival are, however, not always mutually exclusive. There have been a few reports of insects that were apparently freezing tolerant switching to being freeze avoiding. The overwintering larvae of a beetle from northern Indiana, when studied in the winters of 1977-1979. froze at -8°C to -12°C but survived down to -28°C. When examined again in 1982, however, they froze and were killed at -26°C, apparently switching from a freezing-tolerant to a freeze-avoiding strategy during the intervening years. There are adaptations in common between freeze-avoiding and freezing-tolerant insects that may make it easy to switch between the two strategies. It must be said, however, there has been only one other report of an insect, another beetle, displaying a shift in strategy of this sort. One Antarctic nematode is freezing tolerant when immersed in water but, when free of surface water, there is, of course, no inoculative freezing and it can survive by avoiding freezing. The cold-tolerance strategy displayed thus depends on the particular characteristics of the animal's microenvironment.
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