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TPO65阅读Passage 1完整原文完整,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TPO65阅读Passage 1完整原文,希望对大家有所帮助!
托福TPO65阅读Passage 1完整原文
The Pit Organs of Snakes
■It is thought that the facial pits or pit organs on the head of some snakes are specialized infrared(heat) receptors. BWhen a rattlesnake strikes, the direction of the strike seems to be guided by the infrared radiation from its prey.・A rattlesnake strikes only at warm-blooded prey, and when the prey is dead and at room temperature, the snake will not strike. ■ However, a blindfolded snake strikes correctly at a dead rat that is pulled across the cage, provided the rat is warmer than the surroundings. Blindfolded, the snake cannot be guided by vision; nor is it guided by the sense of smell, for it will strike correctly even at a moving, cloth-wrapped electric bulb. The pit organs are evidently involved in sensing the location of warm objects. All snakes that have pit organs feed preferentially on warm-blooded prey, and this further supports the view that these organs are infrared sensors. In the rattlesnake the pit organs are located, one on each side, between the nostril and the eye: they are connected to many nerves, and this in itself suggests a sensory role for the organ.
The sensitivity of the facial pit has been examined by recording the activity in the nerve leading from the organ. A variety of stimuli, such as sound, vibration, or light of moderate intensity (with the infrared part of the spectrum filtered out) , has no detectable effect on the activity in the nerve. However, if objects of a temperature different from the surroundings are brought into the receptive field around the head, there is a striking change in nerve activity, regardless of the temperature of the intervening air.
How is the infrared radiation sensed? The pit is covered by a thin transparent membrane, and it has been suggested that a rise in temperature in the pit behind the membrane could cause an expansion of the gas with a consequent deformation of the membrane. This in turn could be sensed by a suitable receptor. This hypothesis is highly improbable, for a cut in the membrane that opens the pit to the outside air causes no loss in responsiveness, a result that is incompatible with the hypothesis that a pressure change is sensed.
We are left with two other possibilities to consider: Either the effect is photochemical, which means that infrared radiation is absorbed by a specific compound, analogous to the light-sensitive pigments in the eye, or the pit organs are sensitive to the slight temperature rise caused when the infrared radiation reaches it. The infrared radiation emitted from a mammalian body has low-quantum energy, which makes any photochemical effect on pigment extremely unlikely. Pure infrared radiation can be produced by a laser, and experiments with such radiation of known wavelength provide strong evidence that the mode of reception in the facial pit organ is entirely thermal.
Can the pit organs be used for perception of the infrared source in the way our two eyes are used for stereoscopic vision? This seems likely, not only from the observation of the precision with which a snake can strike but also from studies of its brain activity. When infrared radiation falls on the facial pit organ, electric activity can be recorded from the optic tectum, the part of the brain with which the optic nerve is connected. This in itself is suggestive; although the nerves from the pit organ are completely separate from the optic nerves, the same part of the brain seems to handle visual information, which is known to be stereoscopic, and infrared information. The optic tectum has left and right parts, located on either side of the brain. Each part receives input from each eye via the optic chiasma, the point at which the optic nerves from the left and right eye meet. Many of the neurons in the tectum respond to stimulation of the pit organ on the opposite side of the head. This is reminiscent of the way information from the eyes is handled; the crossover of the optic nerve in the optic chiasm a is essential for stereoscopic vision and interpretation of distance. Information from the two pit organs is apparently coordinated and interpreted in a similar way, a conclusion in agreement with recorded changes in the neural activity in the tectum when the infrared source is in a position to irradiate both pits at once. It therefore appears that the facial pits indeed provide stereoscopic perception and substantially aid in the precision of estimating the location of prey.
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