GMAT阅读模拟试题考前练习2

>>GMAT模拟题练习：GMAT阅读模拟试题考前练习2

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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.

2、According to the passage, one reason that the distribution of blood in the sea snake changes little while the creature remains in the ocean is that

A.the heart of the sea snake tends to be located near the center of its body

B.pressure gradients in the water surrounding the sea snake counter the effects of vertical pressure gradients within its blood vessels

C.the sea snake assumes a vertical posture less frequently than do the terrestrial and the arboreal snake

D.the sea snake often relies on waves of muscle contractions to help move blood from the torso to the head

E.the force of pressure gradients in the water surrounding the sea snake exceeds that of vertical pressure gradients within its circulatory system

正确答案：B

GMAT阅读题目解析

题目释义：

细节题目

考点：

支持主题(Supporting ideas)

旨在考察我们对文章细节的认知

这个题目答案定位在第二段“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.”答案选项几乎是这句话的意译。

选项分析：

(A) 海蛇的心脏在其身体中部附近。这个选项的关键词出现在文章的第三段。但是这并非是海蛇血液分配均匀的原因，相反的，这是陆蛇适应性的一个表现。

(B) Correct. 重力与海洋的浮力相互抵消。这个考点中解释了，此处不做赘述了。

(C) 海蛇相比于陆蛇和树蛇，不经常摆竖直pose。这个选项的依据是第三段说树蛇经常摆竖直pose。不过同样，文中并没有说这点是海蛇血液分布均匀的原因，其实海蛇无论什么pose，都没事，因为浮力会抵消重力。

(D) 海蛇经常通过肌肉的收缩让来让血液从身体流入大脑。这个是树蛇的办法，不是海蛇的办法。

(E) 海洋的浮力比重力的力量要强。找回定位句，有“similar”一词，所以这个“exceeds”是错误的。

以上内容就是此次分享的GMAT阅读练习题的内容了，大家做完了吗？想要找更多的练习题就来坦途网GMAT考试频道吧，小编在这与你不见不散哦！