-
archit.job
- Newbie | Next Rank: 10 Posts
- Posts: 5
- Joined: Tue Jan 03, 2012 5:18 am
This is an OG question and I require help with two pretty confusing questions..
Passage:
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
(5)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
(10)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
(15)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
(20)drops signifi cantly, 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
(25)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
(30)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
(35)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
(40)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
(45)apparently improve the fl ow of venous blood
returning to the heart.
1) The passage provides information in support of which
of the following assertions?
(A) The disadvantages of an adaptation to a
particular feature of an environment often
outweigh the advantages of such an adaptation.
(B) An organism's reaction to being placed in an
environment to which it is not well adapted can
sometimes illustrate the problems that have
been solved by the adaptations of organisms
indigenous to that environment.
(C) The effectiveness of an organism's adaptation to
a particular feature of its environment can only
be evaluated by examining the effectiveness
with which organisms of other species have
adapted to a similar feature of a different
environment.
(D) Organisms of the same species that inhabit
strikingly different environments will often adapt
in remarkably similar ways to the few features of
those environments that are common.
(E) Different species of organisms living in the same
environment will seldom adapt to features of
that environment in the same way.
[spoiler]OA:B[/spoiler].Kindly explain why C cannot be a pssibility.
2)The author describes the behavior of the circulatory
system of sea snakes when they are removed from
the ocean (see lines 17-20) primarily in order to
(A) illustrate what would occur in the circulatory
system of terrestrial snakes without adaptations
that enable them to regulate their blood
pressure in vertical orientations
(B) explain why arboreal snakes in vertical
orientations must rely on muscle contractions to
restore blood pressure to the brain
(C) illustrate the effects of circulatory failure on the
behavior of arboreal snakes
(D) illustrate the superiority of the circulatory
system of the terrestrial snake to that of the sea
snake
(E) explain how changes in spatial orientation can
adversely affect the circulatory system of
snakes with hearts located in relatively close
proximity to their heads
[spoiler]OA: A.[/spoiler]..Why cannot E be a pssibility.
Kindly explain thank you so much.....
Passage:
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
(5)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
(10)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
(15)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
(20)drops signifi cantly, 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
(25)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
(30)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
(35)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
(40)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
(45)apparently improve the fl ow of venous blood
returning to the heart.
1) The passage provides information in support of which
of the following assertions?
(A) The disadvantages of an adaptation to a
particular feature of an environment often
outweigh the advantages of such an adaptation.
(B) An organism's reaction to being placed in an
environment to which it is not well adapted can
sometimes illustrate the problems that have
been solved by the adaptations of organisms
indigenous to that environment.
(C) The effectiveness of an organism's adaptation to
a particular feature of its environment can only
be evaluated by examining the effectiveness
with which organisms of other species have
adapted to a similar feature of a different
environment.
(D) Organisms of the same species that inhabit
strikingly different environments will often adapt
in remarkably similar ways to the few features of
those environments that are common.
(E) Different species of organisms living in the same
environment will seldom adapt to features of
that environment in the same way.
[spoiler]OA:B[/spoiler].Kindly explain why C cannot be a pssibility.
2)The author describes the behavior of the circulatory
system of sea snakes when they are removed from
the ocean (see lines 17-20) primarily in order to
(A) illustrate what would occur in the circulatory
system of terrestrial snakes without adaptations
that enable them to regulate their blood
pressure in vertical orientations
(B) explain why arboreal snakes in vertical
orientations must rely on muscle contractions to
restore blood pressure to the brain
(C) illustrate the effects of circulatory failure on the
behavior of arboreal snakes
(D) illustrate the superiority of the circulatory
system of the terrestrial snake to that of the sea
snake
(E) explain how changes in spatial orientation can
adversely affect the circulatory system of
snakes with hearts located in relatively close
proximity to their heads
[spoiler]OA: A.[/spoiler]..Why cannot E be a pssibility.
Kindly explain thank you so much.....
