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# Marine biologists have long thought that variation in the

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Marine biologists have long thought that variation in the [#permalink]

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09 Dec 2011, 17:07
00:00

Difficulty:

65% (hard)

Question Stats:

59% (02:26) correct 41% (02:10) wrong based on 17 sessions

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Marine biologists have long thought that variation in the shell color of aquatic snails evolved as a protective camouflage against birds and other predators. Brown shells seem to be more frequent when the underlying seafloor is dark-colored and white shells more frequent when the underlying seafloor is light-colored. A new theory has been advanced, however, that claims that shell color is related to physiological stress associated with heat absorption. According to this theory, brown shells will be more prevalent in areas where the wave action of the sea is great and thus heat absorption from the Sun is minimized, whereas white shells will be more numerous in calmer waters where the snails will absorb more heat from the Sun's rays.
Evidence that would strongly favor the new theory over the traditional theory would be the discovery of a large majority of
(A) dark-shelled snails in a calm inlet with a dark, rocky bottom and many predators
(B) dark-shelled snails in a calm inlet with a white, sandy bottom
(C) light-shelled snails in an inlet with much wave action and a dark, rocky bottom
(D) light-shelled snails in a calm inlet with a dark, rocky bottom and many predators
(E) light-shelled snails in a calm inlet with a white, sandy bottom and many predators
[Reveal] Spoiler: OA
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10 Dec 2011, 01:00
I got A, wrong choice. But now I understand why correct choice is D. Let's I try to reason:

(A) dark-shelled snails in a calm inlet with a dark, rocky bottom and many predators => in calm inlet is contradict with the argument, so wrong
(B) dark-shelled snails in a calm inlet with a white, sandy bottom => calm inlet is also wrong
(C) light-shelled snails in an inlet with much wave action and a dark, rocky bottom => should be dark-shell snails
(D) light-shelled snails in a calm inlet with a dark, rocky bottom and many predators => light in calm inlet. Dark, rocky, and many predators prove this species successfully avoid the recognition of predator. Rocky bottom also help snail absorb more heat from sun than sandy bottom. So, correct one.
(E) light-shelled snails in a calm inlet with a white, sandy bottom and many predators => same reason as A, B, and C.
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Re: Biology   [#permalink] 10 Dec 2011, 01:00
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