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In terrestrial environments, gravity places special demands on the cardiovascular systems of animals. Gravitational pressure can cause blood to pool in the lower regions of the body, making it difficult to circulate blood to critical organs such as the brain. Terrestrial snakes, in particular, exhibit adaptations that aid in circulating blood against the force of gravity.
The problem confronting terrestrial snakes is best illustrated by what happens to sea snakes when removed from their supportive medium. Because the vertical pressure gradients within the blood vessels are counteracted by similar pressure gradients in the surrounding water, the distribution of blood throughout the body of sea snakes remains about the same regardless of their orientation in space, provided they remain in the ocean. When removed from the water and tilted at various angles with the head up, however, blood pressure at their midpoint drops significantly, and at brain level falls to zero. That many terrestrial snakes in similar spatial orientations do not experience this kind of circulatory failure suggests that certain adaptations enable them to regulate blood pressure more effectively in those orientations.
One such adaptation is the closer proximity of the terrestrial snake’s heart to its head, which helps to ensure circulation to the brain, regardless of the snake’s orientation in space. The heart of sea snakes can be located near the middle of the body, a position that minimizes the work entailed in circulating blood to both extremities. In arboreal snakes, however, which dwell in trees and often assume a vertical posture, the average distance from the heart to the head can be as little as 15 percent of overall body length. Such a location requires that blood circulated to the tail of the snake travel a greater distance back to the heart, a problem solved by another adaptation. When climbing, arboreal snakes often pause momentarily to wiggle their bodies, causing waves of muscle contraction that advance from the lower torso to the head. By compressing the veins and forcing blood forward, these contractions apparently improve the flow of venous blood returning to the heart.
【OG18-P383-442题】The passage provides information in support of which of the following assertions?
我有更好的解析 
暂无雷哥网文字解析
A错误，文中未提及适应性的优势和劣势
B正确，第二段正是通过说明海蛇离开海水后血压遇到的问题来说明陆地蛇是如何应对这个问题的
C错误，only未提及
D错误，will often adapt in remarkably similar ways与文章意思相反
E错误，Different species of organisms living in the same environment文章未提及
outweigh超过；indigenous本土的，本地的；seldom很少地。 A选项：文章并没有比较优劣势，而且感觉文章还是比较支持adaptation的优势的。 B选项：是正确的选项。比较tricky的点是选项说”in an environment to which it is not well adapted“我心想不是通过拉近心脏和头的距离很好的适应了吗？但后来想想，其实还是没有“完美”的适应，因为从心脏到尾巴的循环需要更多的effort。-- 这都是小问题，通过排除法还是可以对比出这是正确的选项的。 C选项：文章没有提到other species，无关。 D选项：比较tricky，后来才想明白 -- 文中并没有提到同一物种在不同环境中会形成相似的adaptation，arboreal snakes就是陆地蛇，何来相似的adaptation? E选项：文章没有提到过其他species，无关。
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2022-10-01 19:53:00
The problem confronting terrestrial snakes is best illustrated by what happens to sea snakes when removed from their supportive medium. Because the vertical pressure gradients within the blood vessels are counteracted by similar pressure gradients in the surrounding water, the distribution of blood throughout the body of sea snakes remains about the same regardless of their orientation in space, provided they remain in the ocean. 说的就是B的意思
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2019-09-17 20:48:21
反正法
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2018-12-06 20:21:22
太绕了
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2018-11-29 16:01:31
感觉不会
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2018-08-24 15:43:15
路蛇和水蛇不是同一个物种
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2018-05-17 04:32:53
默默回复默默
E也不对
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2018-05-17 04:33:05
默默回复默默
排除法有用
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2018-05-17 04:33:14
你猜猜我猜不猜回复默默
是吗
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2018-08-24 15:43:01
想问一下大家 当遇到这种题目怎么办 总不能再看一遍吧
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2018-03-30 15:32:31
默默回复( ¨̮ )
A 不是主要内容
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2018-05-17 04:22:44
默默回复( ¨̮ )
C用了only 就会对正确性大打折扣
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2018-05-17 04:30:00
默默回复( ¨̮ )
Ｂ有 some times, 会增大正确度
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2018-05-17 04:32:09
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