Sat practice Test #8 Answer Explanations

Choice A is the best answer. The first two paragraphs of the passage 
describe the physical process by which the Venus flytrap closes its trap 
but also note certain long-standing questions about that process: “How 
does the plant encode and store the information from the unassuming 
bug’s encounter with the first hair? How does it remember the first 
touch in order to react upon the second?” The passage then answers 
those questions by discussing, in the third and fourth paragraphs, a 
study conducted by Dieter Hodick and Andreas Sievers that identified 
the physiological means behind the closing of the Venus flytrap’s trap 
and, in the last paragraph, a study conducted by Alexander Volkov that 
confirmed and built on Hodick and Sievers’s findings. The primary 
purpose of the passage can therefore be seen as discussing scientific 
findings that explain how the Venus flytrap closes its trap.
Choice B is incorrect because the passage doesn’t discuss the Venus 
flytrap’s ability to close its trap in the context of the abilities of other 
plants. Choice C is incorrect because the passage discusses how 
the closing action operates but not how it has evolved. Choice D is 
incorrect because the passage doesn’t provide an overview of the 
Venus flytrap and its predatory behavior; it merely notes in passing 
that the closing action has a predatory function.

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QUESTION 43
Choice C is the best answer. The first paragraph discusses the 
challenge posed to the Venus flytrap by the opening and closing of 
its trap: “Closing its trap requires a huge expense of energy, and 
reopening the trap can take several hours, so Dionaea only wants 
to spring closed when it’s sure that the dawdling insect visiting its 
surface is large enough to be worth its time.” Since closing and 
reopening the trap requires the expense of precious energy, it can 
be inferred that by guarding against unnecessary closing, multiple 
triggers safeguard the plant’s energy supply.
Choice A is incorrect because the passage never indicates that multiple 
triggers allow the Venus flytrap to identify which species its prey 
belongs to, only that they allow it to gauge the prey’s size. Choice B is 
incorrect because although the passage implies that the plant needs 
to conserve energy and indicates that calcium is involved in the trap-
closing mechanism, there is no indication that the plant’s calcium 
reserves themselves require conservation. Choice D is incorrect 
because it can be inferred from the passage that the advantage of 
multiple triggers is that they prevent the Venus flytrap from closing on 
the improper prey rather than from prematurely closing on the proper 
prey; the passage never implies that when touched by its proper prey, 
the Venus flytrap is at risk of closing too soon to capture it.
QUESTION 44