The passage provides information on each of the following EXCEPT

A tall tree can transport a hundred gallons of water a day from its roots deep underground to the treetop. Is this movement propelled by pulling the water from above or pushing it from below? The pull mechanism has long been favored by most scientists. First proposed in the late 1800s, the theory relies on a property of water not commonly associated with fluids: its tensile strength. Instead of making a clean break, water evaporating from treetops tugs on the remaining water molecules, with that tug extending from molecule to molecule all the way down to the roots. The tree itself does not actually push or pull; all the energy for lifting water comes from the sun’s evaporative power.

The passage provides information on each of the following EXCEPT

  1. when the pull theory originated
  2. the amount of water a tall tree can transport
  3. the significance of water’s tensile strength in the pull theory
  4. the role of the sun in the pull theory
  5. the mechanism underlying water’s tensile strength

An important thing to keep in mind about the Reading Comprehension section of the GRE as we use PowerPrep online to study is that it is just that—reading comprehension. In other words, as difficult as it may seem, and it can be pretty tricky, the test makers will always give us all the information we need in the passage to answer the question. Questions that ask us about specific details of the passage, like number 18 on the second Verbal section of practice test 1, are a prime example.

Slow down! Even though it’s in ALL CAPS, we all, at one time or another, miss the “EXCEPT” part of an EXCEPT question. One way to make sure that we don’t get a question like this wrong is to make sure to read all of our answer choices. Then, when it seems as though more than one is something the passage provides information about, we might look back and notice that the question said “EXCEPT.” So, this question in particular wants to know what the passage does not provide information about.

Since we don’t have any keywords in the question itself, we can rely on keywords in our answers to help us navigate for the information we need in the passage. In order to answer this question about details, we’ll want to quickly read through the passage. We don’t need to understand every detail because, again, we can look back in the passage for those details that are specifically referenced in our question. However, we’ll want to make sure we have a general idea of the passage.

This passage starts by presenting a fact (that trees transport a whole lot of water every day) and presenting two different possible explanations for this phenomenon in the form of a question. Then, the passage provides support for one view (the “pull mechanism”) by briefly explaining how it would work given our knowledge of a particular property of water (“its tensile strength”).

Cool! Now that we’ve read the passage, we are better equipped to figure out which answer the passage did not provide any information about.

  • when the pull theory originated

We might remember a detail about this, but just to be sure we aren’t getting mixed up, we could skim the passage for any dates or references to the “pull theory” specifically. Aha! The fourth sentence begins “first proposed in the late 1800s,” which is an introductory phrase that comments on the subject of the sentence, “the theory.” Wait. Which theory? We may need to go backwards a sentence to note that the previous sentence talks about “the pull mechanism.” So, the “theory” we’re talking about IS the pull theory, and we are told it was “first proposed,” or originated in the 1800s. We can eliminate A because the passage does provide information about this subject.

  • the amount of water a tall tree can transport

If we aren’t sure whether or not the passage discusses how much water a tree can transport, we might skim for units of measurement typically associated with water. Ohp! The first sentence tells us that “a tall tree can transport a hundred gallons of water a day.” We can eliminate B because the passage does provide information about this subject.

  • the significance of water’s tensile strength in the pull theory

Hmm. Water having a particular property was a pretty crucial detail in the passage, and indeed, if we skim the passage for references to “tensile strength,” we’ll note that the fourth sentence tells us that the pull theory “relies” on this property. So, we do know from the passage that the tensile strength of water is pretty significant as far as the pull theory is concerned. We can eliminate C.

  • the role of the sun in the pull theory

Wait. We don’t remember any references to the “sun” in the passage, so is it possible this is our answer? Let’s skim for things related to the sun. Ahh. The very last sentence mentions the “sun’s evaporative power” as the source of energy behind the pull theory. Pretty sneaky since it was at the end, but this information is definitely in there. We can eliminate D.

  • the mechanism underlying water’s tensile strength

Well, we’ve eliminate ALL of our previous answers, so it seems like this should probably be it. We DO know from the passage that water’s tensile strength is what gives it the ability to pull water up from lower in the tree as it evaporates, but are we ever told about the “mechanism behind” this property of water? In other words, do we know what about water gives it this property when the passage said this is not a property common to fluids? Nope. If we happen to know how water achieves this property, it could be easy to assume that the passage addressed that, but skimming through the passage (particularly around the fourth and fifth sentences that talk about tensile strength) we’ll find that the passage never addresses how this strength is achieved. Answer E must be correct since there is not information about the “mechanism behind water’s tensile strength” in the passage.

So E is the correct answer, but another tip about EXCEPT questions that we learned is that we should always remember to check the beginning and end of passages for details if we aren’t sure whether or not they were mentioned in the passage.

 

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